Conference Abstracts

All Abstracts were presented at the Groundwater Conferences

Displaying 651 - 700 of 795 results

Title	Presenter Name	Presenter Surname	Area	Conference year Sort ascending	Keywords
'Best Practice' Approach To Undertaking Detailed Groundwater Impact Assessment Studies For Proposed Solar Energy Plants	Sheila	Imrie	Jacobsdal, Free State	2015	Solar energy, EIA, best practice, groundwater management
Abstract South Africa is a country at the forefront of the solar energy revolution. Each solar energy plant implementation results in further supply of clean renewable energy to the South African electric grid, thus playing a part in helping South Africa meet its renewable energy targets, in addition to stimulating long-term economic development and creating new jobs. Active solar techniques include the use of photovoltaic systems, concentrated solar power and solar water heating to harness the energy. Particular focus has recently been on the use of concentrated solar power technology which is better able to address the issues of scalability and electric storage. The process includes the use of a liquid salt solution and also requires a reliable water source. When applying for a new solar energy plant, a geohydrological assessment is required to inform the Environmental Impact Assessment. SolarReserve South Africa (Pty) Ltd responsibly take this one step further by requesting detailed geohydrological assessments including drilling and field testing, numerical modelling and simulations, and detailed impact analysis. Of particular consideration in these assessments is the potential for groundwater to meet the plants water needs, as well as the assessment of risk and potential groundwater contamination impact from failure in the lining of the evaporation ponds. This paper describes the 'best practice' approach that has been formulated and undertaken for some previously proposed sites, and is now recommended for future use in the groundwater impact assessment of future proposed solar energy plants in South Africa. It makes use of a SolarReserve case study example, located at the farm Kalkaar near Jacobsdal in the Free State Province, to explain the main steps in the process and how the results of using this approach are important inputs in the assessment of impacts, decision-making regarding go/no-go, technology used, infrastructure and site layout, and responsible management and monitoring of the groundwater in the future.
Using Gravity Anomalies from Grace to Estimate Changes in Groundwater Storage In The Vaal River Basin	Khuliso	Masindi	Gauteng	2015	GRACE
Abstract The Gravity Recovery and Climate Experiment satellites detect minute temporal variation in the earth’s gravitational field at an unprecedented accuracy, in order to make estimation of the total water storage (TWS). GRACE provides a unique opportunity to study and monitor real time water variation in the hydrologic stores( snow, groundwater, surface water and soil moisture) due to increase or decrease in storage. The GRACE monthly TWS data are used to estimate changes in groundwater storage in the Vaal River Basin. The Vaal River Basin has been selected because it is one of the most water stressed catchment in South Africa; it is well-renowned for its high concentration of industrial activities and urbanized zones. Therefore, in order to meet future water demands it is critical to monitor and calculate changes in groundwater dynamics as an important aspect of water management, where such a resource is a key to economic development and social development. Previous studies in the Vaal River Basin, where mostly localized focusing largely on groundwater quality and to a lesser extent groundwater assessment. Hydrological models have been generated for the whole of South Africa, many of this models does not take into account the groundwater. Thus, there is a significant gap in our understanding of surface and ground water dynamics in the Vaal River Basin. The paucity of data and monitoring networks is often the limitation in calculating changes in water storage over a large area, particularly in Africa. In this scenario GRACE is the only approach to estimate changes in hydrological stores as it covers large areas and generate real time data. It does not require information on soil moisture, which is often difficult to measure. The preliminary results indicate that the change in TWS anomaly derived from GRACE data is - 12.85 mm of vertical column of water at 300 km smoothing radius. The change in groundwater storage is calculated by incorporating hydrologic components to the TWS (work in progress). The results obtained from this study will be compared to existing hydrological models and results generated from models applicable to the semi-arid region of South Africa. It is anticipated that this satellite observation technique, GRACE, will provide an accurate estimate of change in groundwater storage. Furthermore, it will show the usefulness of satellite based techniques for improving our understanding of groundwater dynamic, which will improve water management practices.
Hydrodynamic and Hydrochemical characterization of groundwater resources of a municipality in Switzerland	Cedric	Meier	Switzerland	2015
Abstract The study characterized the hydrodynamic and hydrochemical properties of the quaternary porous aquifer which supplies the municipality of Pont-en-Ogoz (Department of Fribourg in Switzerland) with drinking water. The hydrostratigraphic series is composed of a thin overburden material, a porous aquifer composed of gravel and sand, a thin silt-clay layer and sandstone that forms the deeper aquifer. Pumping tests of a borehole nearby the well PSG1 and well PSG1 itself was used to calculate a mean hydraulic conductivity of the aquifer. The hydraulic conductivity from the test varies between 7.4?10-7 m/s and 2.4?10-5 m/s. The values of hydraulic conductivities are typical for sedimentary rocks as silt, fine sandstone and fine sand. The main physical and chemical parameters like concentration in cations and anions, as well the pH, the dissolved oxygen, the electrical conductivity and the alkalinity were measured and saturation indices were calculated. The analysis of the physical and chemical parameters shows that the type of water is Ca-HCO3 and that it contain mixture of old water coming from a regional groundwater flow system, probably from the deeper aquifer, and from recently infiltrated water as local groundwater flow system. The quality of water is generally good, but the effect of the purification of it through the thin overburden layer is limited. An initial one dimension steady state models based on the hypothesis of Dupuits for an unconfined and confined aquifer was used to calculate the mean recharge. This model gives us a recharge values from 24.8 cm/year and 12.1 cm/year, respectively. A second, two dimensional, confined, homogeneous and isotropic model has been calibrated in order to represent the spatial distribution of the piezometric surface. All the models have been calibrated as a steady state. Two groups of predictive scenarios were done to evaluate the drawdown in the well PSG1 using the 2D model. The maximum drawdown calculated was 40 m for the first group of scenarios and 3-4 m for the second group. The second group of scenarios considered from the deeper sandstone aquifer contributing to the well PSG1. The results of the second group of scenarios fit the field results better and the capture zone is much smaller than the one from the first model. The reality is probably between those two models. In order to lower the uncertainty, spatial variation should be added
Interannual variability in rainfall isotope composition as a tracer of spring water flow.	Roger E	Diamond	Western Cape	2015	Table Mountain Group, springs, rainfall isotopes
Abstract Table Mountain reaches 1086m elevation, the upper half of which comprises Table Mountain Group (TMG) quartzite with extensive fracture porosity. The lower half of the mountain comprises a mixture of Cape Granite intruded into Malmesbury Group metapelites, both of which are poor aquifers, but are in places overlain by scree slopes predominantly composed of TMG quartzite boulders. The region experiences a Mediterranean climate with warm, dry summers and cold, wet winters, with rainfall ranging from 600-1600mm/a depending largely on proximity to the mountain. Several springs issue from the slopes of the mountain, ranging in elevation from 15-410masl and in flow from non-perennial to 30L/s. Water chemistry reveals very little about spring water flow, as the waters have very low dissolved solids. Samples of 10 of these springs were taken twice per year for 3 years while rainwater was sampled at 120masl at the University of Cape Town (UCT) and at 1074masl at the Upper Cableway Station. These samples were analysed for oxygen and hydrogen stable isotope composition, mostly by mass spectrometer, but also by laser spectroscopy. The isotope results reveal an altitude gradient between the two rainfall stations of -0.075?/100m for ?D and -0.48?/100m for ?18O. Employing this isotope gradient, the average recharge altitude for the springs is 304masl, compared to an average discharge altitude of 156masl. Using this difference in altitude and the average slope of the terrain, a typical flow path of 1km from recharge to discharge point can be derived. Additionally, there are shifts in the weighted annual mean isotope composition of rainfall at UCT. For the years 2010-2012, the shifts are paralleled by similar shifts in the mean isotope composition at the springs for each of those years. This suggests rainfall discharges in the same winter season it has been recharged. In combination with the evidence for long term reliability of some of the springs over the dry season and during droughts, this suggests a layered flow of groundwater in the scree aquifer, allowing both long term steady discharge of deeper groundwater, as well as short term discharge of recently recharged rain. In combination with the flow path derived above, hydraulic conductivities in the realm of 10-20m/d can be calculated for the scree aquifers.
Governing Groundwater Wisely To Provide For Current And Future Generations.	Zine	Matshakeni		2015
Abstract POSTER About 97% of the earth's freshwater fraction is groundwater, excluding the amount locked in ice caps (Turton et al 2007) and is often the only source of water in arid and semi-arid regions and plays a critical role in agriculture, this dependency results in over-exploitation, depletion and pollution (Turton et al 2007). Groundwater governance helps prevent these issues. CSIR defines governance as the process of informed decision making that enables trade between competing users of a given resource, as to balance protection and use in such a way as to mitigate conflicts, enhance security, ensure sustainability and hold government officials accountable for their actions (Turton et al 2007). Realising the issues of groundwater governance is a requirement for developing policy recommendations for both national and trans-boundary groundwater governance. Groundwater level decline has led to depletion in storage in both confined and unconfined aquifer systems (Theesfeld 2010). There are about six institutional aspects, namely voluntary compliance, traditional and mental models, administrative responsibility and bureaucratic inertia, conflict resolution mechanisms, political economy and information deficits (Theesfeld 2010). Each of these aspects represents institutional challenges for national and international policy implementation. Traditional local practices should not be disregarded when new management schemes or technological innovations are implemented. The types of policies that impact governance include regulatory instruments, economic instruments and voluntary/advisory instruments. Regulatory or command and control policy instruments such as ownership and property right assignments and regulations for water use are compulsory. Economic policy instruments make use of financial reasons such as groundwater pricing, trading water right or pollution permits, subsidies and taxes. Voluntary /advisory policy instruments are those that influence voluntary actions or behavioural change without agreement or direct financial incentives. These are ideal types though no policy option ever relies purely on one type of instrument. The aim of these policies is to have an impact on governance structures (Theesfeld 2010). The national water act (1998) of the Republic of South Africa is not widely recognized as the most comprehensive water law in the world even though it is the highlight of socio-political events; socially it is still recent in most sites although the law was implemented 15 years ago (Schreiner and Koppen 2002). Regulations for use include quantity limitations, drilling permits and licensing, use licenses, special zone of conservation and reporting and registering requirement. In general when drilling and well construction are done commercially they increasingly fall under the scope of regulatory legislation. This paper will focus mostly on traditional and mental models; procedures that a certain community is dependent on should be taken into account before replacing with technological advanced tools. Consultation of the public can cause conflicts which lead to poor groundwater management. Keywords: Groundwater governance, policy, policy instruments.
Potential for co-disposal of fly-ash and coal discard: Results from geochemical modelling and laboratory studies	Meris	Mills		2015
Abstract Geochemical investigations for a planned coal mine indicated that the coal discard material that would be generated through coal processing would have a significant potential to generate acid rock drainage. A power station is planned to be developed in close proximity to the coal mine, and the potential for co-disposal of coal discard with fly-ash material required examination. Fly-ash is typically highly alkaline and has the potential to neutralise the acidic coal discard material. In order to investigate whether this was a viable option, the geochemical interaction between the coal discard and fly-ash was investigated. Geochemical data, including acid-base accounting, total chemical compositions, leach test data and kinetic test data, were available for the coal discard material and the fly-ash. Using these data as inputs, a geochemical model was developed using Phreeqci to predict the pH of leachate generated by mixing different ratios of coal discard and fly-ash. The ratio of coal discard to fly-ash was established that would result in a leachate of neutral pH. Using this prediction, a kinetic humidity cell test was run by a commercial laboratory for a total of 52 weeks using the optimal modelled ratio of discard and fly-ash. Although leachate pH from the kinetic test initially reflected a greater contribution from fly-ash, the pH gradually decreased to the near-neutral range within the first 20 weeks, and then remained near-neutral for the remainder of the 52-week test. During this period, sulphate and metal concentrations also decreased to concentrations below those generated by either the fly-ash or coal discard individually. The addition of fly-ash to the coal discard material provided sufficient neutralising capacity to maintain the near-neutral pH of the co-disposal mixture until the readily available sulphide minerals were oxidized, and the oxidation rates decreased. At the end of the test, sufficient neutralising potential remained in the humidity cell to neutralise any remaining sulphide material. The results of this investigation suggested that, under optimal conditions, co-disposal of fly-ash with coal discard is a viable option that can result in reduced environmental impacts compared to what would be experienced if the two waste materials were disposed of separately.
Modelling recharge in an opencast coal mining environment, applying model parameters on a catchment scale.	Freek	van Devnter		2015
Abstract The provision, usage and discharge of water resources are major concerns for coal mines, both underground and opencast. Water resources in a coal mining environment will often account for a significant portion of the daily operational cost. In order to cut costs, the mine will often collect as much runoff as possible to recycle for future use. This on-going recycling of site water and management of the resource demands a complete site water balance model in order to understand the dynamics of the resource within the boundaries of the mine. To improve the understanding of the dynamics of the resource on a much larger scale, and the effect it will have on recharge in an open cast coal mine environment, one must consider alternative modelling approaches which can compensate for such conditions. This amounts to describing recharge as a modelling component in a physically based distributed model. The main goal of this project is to calculate recharge into the main pit at this specific colliery by applying parameters on a quaternary catchment scale. The colliery is located just west of the town of Ogies, Mpumalanga on the peripheral region of the quaternary catchment B20G. The physiography of the quaternary catchment B20F is described as a central Highveld region gently sloping to the north. The geohydrological modeling application MIKE SHE (developed by DHI) was used to develop a fully integrated catchment model. The model was created mainly to simulate the impact of human activities on the hydrological cycle and hence on water resource development and management. Different modules of MIKE SHE that was used during the modelling stage include saturated- and unsaturated flow and a small degree of overland flow. Key words: Mpumalanga, MIKE SHE, recharge
Application of GIS Mapping Techniques to Classify Karoo Aquifers	Mildred	Goes		2015
Abstract POSTER As the National Water Act has evolved to provide for more effective and sustainable management of our water resources, there has been a shift in focus to more strategic management practices. With this shift come new difficulties relating to the presentation of sensitivity issues within a spatial context. To this end it is necessary to integrate existing significant spatial layers into one map that retains the context, enables simple interpretation and interrogation and facilitates decision making. This project shows the steps taken to map and identify key groundwater characteristics in the Karoo using Geographic Information Systems (GIS) techniques. Two types of GIS-based groundwater maps have been produced to assist with interpretation of existing data on Karoo Aquifer Systems in turn informing the management of groundwater risks within Shell's applications for shale gas exploration. Aquifer Attribute and Vulnerability maps were produced to assist in the decision making process. The former is an aquifer classification methodology developed by the project team, while the latter uses the well-known DRASTIC methodology. The overlay analysis tool of ESRI's ArcGIS 10.1 software was used, enabling the assessment and spatial integration of extensive volumes of data, without losing the original detail, and combining them into a single output. This process allows for optimal site selection of suitable exploration target areas. Weightings were applied to differentiate the relative importance of the input criteria. For the Attributes maps ten key attributes were agreed by the project team to be the most significant in contributing to groundwater/aquifer characteristics in the Karoo. This work culminated in the production of a series of GIS-based groundwater attributes maps to form the Karoo Groundwater Atlas which can be used to guide groundwater risk management for a number of purposes. The DRASTIC model uses seven key hydrogeological parameters to characterise the hydrogeological setting and evaluate aquifer vulnerability, defined as the tendency or likelihood for general contaminants to reach the watertable after introduction at ground surface.
Characterization of the Pretoria Fountains East and Fountains West Karst Aquifer Compartments	Vevanya	Naidoo	Gauteng	2015
Abstract POSTER The Fountains East and Fountains West groundwater compartments (by means of the Upper and Lower Fountain springs) have been supplying the City of Pretoria with water since its founding in 1855. These adjacent compartments which are underlain by the Malmani dolomites of the Chuniespoort Group are separated by the Pretoria syenite dyke and are bounded to the north by the rocks of the Pretoria Group (Timeball Hill Formation). Swallow holes and paleosinkholes play important roles in recharge in karst environments. Available sinkhole data and geotechnical percussion borehole logs are being collated to compile a detailed conceptual geological model. Inorganic chemistry data (2007 - 2012) as well as spring discharge volumes (2011 - 2012) for the Upper and Lower Fountain springs, supplied by the City of Tshwane Municipality, is being used to characterise the two compartments. This is done by means of piper diagrams, stiff diagrams and temporal plots. Isotope data for the Upper and Lower Fountain springs are available for 1970 to 2007. ?D and ?18O data from the Upper and Lower Fountain springs are plotted against each other and the Global Meteoric Water Line. Other stable isotopes (including 14C and 3H) are also plotted as time trends and interpreted. Interpretation of the combined geotechnical, chemical and isotope data will aid in understanding the karst aquifer and the controls on groundwater system within and possibly between these compartments.
Comparitive analyses between LAK3 package and the high K techniques used for numerical simulation of lake-aquifer interactions	Jannie	Weitz		2015
Abstract Modelling of groundwater systems and groundwater-surface water interaction using advanced simulation software has become common practice. There are a number of approaches to simulate Lake-aquifer interactions, such as the LAK Package integrated into MODFLOW, the high conductivity and fixed stage approaches. LAK and the high conductivity approaches were applied and compared in simulating Lake- aquifer interaction in the Lake Sibayi Catchment, north-eastern, South Africa using the finite difference three-dimensional groundwater flow model, Visual MODFLOW Flex under steady state conditions. The steady state model consisted of two layers: an upper layer consisting of the Sibayi, KwaMbonambi, Kosi Bay and Port Durnford Formations which have similar characteristics, and a lower model layer representing the karst, weathered and calcareous Uloa Formation. The bottom model boundary is constrained by the impermeable Cretaceous bedrock. The model area covers the surface and groundwater catchments of Lake Sibayi which is constrained in the east by the Indian Ocean. A no-flow boundary condition is assigned to the northern, western and southern sides and a constant head boundary is assigned to the eastern side. The Mseleni River and neighbouring plantations were modelled using the River and Evapotranspiration boundary conditions respectively. Input parameters for the various boundary conditions were obtained from the previously developed high resolution conceptual model, including recharge
Characterise and quantify contamination within the Crocodile (West) and Marico Water Management Areas, South Africa	Chazanne	Allison	Hartebeespoort Dam	2015	Heavy metal, chemical fingerprint, geochemistry
Abstract Define chemical signatures from river waters collected in the Crocodile (West) and Marico Water Management Areas, South Africa. Samples were analysed for anion complexes using Ion Chromatography (IC) and major and trace element chemistry using quadrupole Inductively Coupled Plasma-Mass Spectrometry (q-ICP-MS). Results are used to define the various chemical signatures resulting from activities within the study area which include mining, agriculture, industry, residential and domestic, and recreational usage and to differentiate the 'background' that arises from the natural geological heterogeneity. The aim of this characterisation is to fingerprint the chemical signatures of various anthropogenic activities irrespective of background. Results from this investigation have been mapped using GIS to visualise the data across the study area. Based on the results, the contamination sources within the area can be identified and ranked in terms of their contribution to the total effective contamination received at Hartebeespoort Dam. {List only- not presented}
Arsenic in the west-African water reserves: Investigation into sources of the contaminant through case studies in the region	Andre	van Coller	West Africa	2015	Arsenic
Abstract The mineral rich basin of the West African region has vast reserves of gold, diamond as well as iron ore deposits. Throughout the regional geological setting characterised by structural variations and intrusive belts with metamorphic mineral rich sequences covered by saprolite soils, one common chemical constituent remains a constant in the water reserves. Arsenic is in high concentrations throughout the region with chemical ranges commonly above the various country guidelines as well as international IFC and WHO standards. The aqueous chemical species is associated with arsenopyrite rich mineralogy of the regional greenstone belts and highly weathered soils. This conference article and presentation investigates the natural source of the arsenic through baseline data as well as the effect of mining on the already high concentrations of arsenic in both the groundwater and surface water. Natural levels of various chemical species in the regional area are already high at baseline level. One of the main research questions is thus whether mining and other anthropogenic activities will have an impact on the environment or will the changes to concentrations be so insignificant to allow the ecosystems and water users to continue in their current ways without any effect. Various case studies in Burkina Faso, Liberia, Sierra Leone and other countries have been combined to investigate the arsenic-rich resources of the West African region through groundwater specialist investigative methods with emphasis on geochemical modelling of the fluid-rock and fluid-fluid interactions leading to the water quality in the region.
Use Of Environmental Isotopes To Determine Hydraulic Connectivity Across The Surrounding Aquifers At Majuba UCG	Gundo	Mathoho		2015
Abstract Environmental isotope techniques have been successfully applied in the field of hydrogeology over the last couple of decades and have proved useful for understanding groundwater systems. This paper describes a study of the environmental isotopes for Oxygen (18O) and Hydrogen (1H, 2H-Deutrium, 3H-Tritium) obtained from various points in and around the underground coal gasification (UCG) site in Majuba, South Africa. UCG is an alternative mining method, targeting deep coal seams that are regarded as uneconomical to mine. The process extracts the energy by gasifying the coal in-situ to produce a synthetic gas that can be used for various applications. The site consists of shallow, intermediate and deep aquifer systems at a depth of 70m, 180 and 300m respectively. The intermediate aquifer is further divided into the upper and lower aquifer systems. Samples were taken from each aquifer system together with supplementary samples from the Witbankspruit and an on-site water storage dam. A total of 15 samples were submitted for isotope analyses. By investigating the various isotopic signatures from all the samples taken, it will be possible to determine if there are similar or contrasting isotopic compositions by deducing possible water source for each sample due to isotopic fractionation caused by physical, chemical and biological processes. This will also be supported by deducing the mean residence time (MRT) for each water source sampled based on the Tritium data as well as the chemistry data already available for different sources. The chemistry data established linkages between the upper and lower intermediate aquifers.{List only- not presented} Key words: Environmental isotopes, UCG, Water source, Isotope fractionation
Variability In Kd And How It Relates To The New Guidelines For Contaminated Land	Michelle	Papenfus		2015
Abstract Globally, a growing concern have been that the heavy metal contents of soil are increasing as the result of industrial, mining, agricultural and domestic activities. While certain heavy metals are essential for plant growth as micronutrients, it may become toxic at higher concentrations. Additionally, as the toxic metals load of the soil increases, the risk of non-localized pollution due to the metals leaching into groundwater increases. The total soil metal content alone is not a good measure of risk, and thus not a very useful tool to determine potential risks to soil and water contamination. The tendency of a contaminant to seep into the groundwater is determined by its solubility and by the ratio between the concentration of the contaminant sorbed by the soil and the concentration remaining in solution. This ratio is commonly known as the soil partitioning or distribution coefficient (Kd). A higher Kd value indicate stronger attraction to the soil solids and lower susceptibility to leaching. Studies indicate that the Kd for a given constituent may vary widely depending on the nature of the soil in which the constituent occurs. The Kd of a soil represents the net effect of several soil sorption processes acting upon the contaminant under a certain set of conditions. Soil properties such as the pH, clay content, organic carbon content and the amount of Mn and Fe oxides, have an immense influence on the Kd value of a soil. Kds for Cu, Pb and V for various typical South African soil horizons were calculated from sorption graphs. In most cases there were contrasting Kd values especially when the cations, Cu and Pb, had high contamination levels, the value for V was low. There is large variation between the Kds stipulated in the Framework for the Management of Contaminated land (as drafted by the Department of Environmental Affairs) and the values obtained experimentally in this study. The results further indicate that a single Kd for an element/metal cannot be used for all soil types/horizons due to the effect of soil properties on the Kd. The results for Cu and Pb indicated that the Kds can range in the order of 10 to 10 000 L/kg for Cu and 10 to 100 000 L/kg for Pb. The variation in V Kd was not as extensive ranging from approximately 10 to 1 000 L/kg. {List only- not presented}
Remediation of Groundwater at AngloGold Ashanti South Africa	Gawie	van Dyk		2015
Abstract Gold Mining activities the past 60 years at AngloGold Ashanti polluted the groundwater underlain by 4000 ha of land at the Vaal River and West Wits operations in South Africa. Sulphide material in Tailings Storage Facilities, Waste Rock Dumps and extraction plants produce Saline Mine Drainage with Sulphate, minor salts and metals that seep to the groundwater and ultimately into surface water resources. Water regulation requires mines to prevent, minimise/ reduce or eliminate pollution of water resources. The waste philosophy has matured from tolerate and transfer to treat and termination of pollution sources. The impact of the pollution was determined and possible technologies to treat the impact were evaluated. Source controls of proper water management by storm water management, clean dirty water separation, lined water conveyance structures and reduced deposition of water on waste facilities is crucial. The aquifer character determines the possible remediation technology. From the possible technologies phytoremediation, physical interception and re-use of this water was selected. In future possible treatment of the water would be considered. This paper explain the strategy and report on the phased implementation of these plans and the expected results. The establishment of 750 ha of woodlands as phytoremediation, interception trenches of 1250 m, 38 interception boreholes and infrastructure to re-use this water in 10 water management areas is planned. The total volume of 15 Ml/day would be abstracted for re-use from the boreholes and trenches. The woodlands can potentially attenuate and treat 5 ml/day. The established woodlands of 150 ha proof successful to intercept diffused seep over the area of establishment and reduce the water level and base flow. The 2 implemented trenches of 1000 m indicate a local decline in the water level with interception of shallow groundwater within 1-2 m from surface. The 2 production interception well fields abstracting 50 and 30 l/s respectively indicate a water level decline of between 2 to 14 m with regional cones of depression of a few hundred meters to intercept groundwater flow up to 20 meter. Predictions from groundwater modelling indicate that these schemes can minimise pollution during the operational phase and protect downstream water resources. Predictions from modelling indicate that the pollution sources need to be removed to ensure long term clean-up to return the land to save use. The gold and uranium prize is securing the removal of the sources through re-processing of the tailings and waste rock dumps. After removal of the sources of pollution the remediation schemes would have to be operated for 20 years to return the groundwater to an acceptable standard of stock watering and industrial water use. The water quality is observed by a monitoring network of approximately 100 observation boreholes.
Integration of water simulation modelling for water conservation and demand management in the mining sector (a case study)	Fanie	Botha	South Africa	2015	legislative challenges, integrated modelling, WUL
Abstract This paper outlines and presents out-of-the-box theories as examples to highlight some of the challenging restraints within the current legislative environment preventing scientists, engineers and other operational personnel to take theory into action and implementation. Key to this is the very static nature of the water use license (WUL)and associated process. The first example shows how integrated dynamic water modelling can be utilized to create an integrated water and waste management plan within the mining sector. The models developed using principles from Government Notice 704, the Best Practice Guidelines (BPGs) and the principles of water conservation and demand management. Ultimately it keeps clean and dirty water flows separate and optimises the use of dirty water in order to reduce raw/potable water off-takes through this process. The objective of these models are to optimise the water use and develop strategies to ultimately enable mines to optimize it's internal non-potable water resources therefor relieving pressure on the limited potable systems, as well as aiding surrounding communities, in which they operate, with potable water. Results from the model provides for 1 or 20 years simulation data that differs year-on-year based on numerous factors, i.e. rainfall, run of mine (ROM) feed and growing/declining surface run-off areas. The variability of the results makes it almost impossible to utilize within application documentation as it is too complex and it does not align with the application figures as required in the WUL process. This resulting in a fairly simplistic and sometimes unrealistic static model that is submitted as part of the application.
Hydraulic fracturing and Water Resources: Separating fact from fiction	Lizanne	Bredenkamp	Karoo	2015	Shale gas, Dolerite Intrusions
Abstract Shale gas in South Africa can be a game changer for the Karoo and South Africa economy but it may have a devastating effect on the environment. The Karoo communities is highly reliable on groundwater for their stock, irrigation and also for domestic use. Knowing the process and the potential impacts of gas-well drilling and fracturing on shallow groundwater systems beforehand different appropriate studies can be done before any hydraulic fracturing can took place in South Africa. The biggest concerns with hydraulic fracturing is that the fracturing fluids will flow and discharge into shallow aquifers due to the high pressure used or the produced water mixed with deep saline water may discharge into the environment. This paper presents a baseline dataset that will be a reference point against which any future changes in groundwater concentrations can be measured. The Karoo basin with its numerous dolerite intrusions make it unique and different from other countries. These dolerite intrusions are associated with high yielding boreholes because of the fractured contact. The Karoo Basin may be under artesian conditions, which imply that any pollutant might migrate upwards in the Karoo. The understanding of key attributes for characterising groundwater of Karoo Aquifers is most importantly the depth to water level, the yield, and groundwater quality.. The understanding of these characteristics will help to close possible legislative loopholes regarding fracturing. This paper establish an interactive database to obtain full understanding of the hydrogeology of the Karoo to be able to quantify how much water is available in the Karoo and who is the users. Not only the quantity of the water in the Karoo, but also quality and age/origin by making use of different isotopes in conjunction with basic macro chemistry. This will allow for a broader picture before any unconventional gas mining in the Karoo takes place and it can be used to identify any future changes in groundwater quality and quantity of the Karoo aquifers.
Taking Capture Principle into Practice	Helen	Seyler		2015
Abstract The 'maintainable aquifer yield' can be defined as a yield that can be maintained indefinitely without mining an aquifer. It is a yield that can be met by a combination of reduced discharge, induced recharge and reduced storage, and results in a new dynamic equilibrium of an aquifer system. It does not directly or solely depend on natural recharge rates. Whether long-term abstraction of the 'maintainable aquifer yield' can be considered sustainable groundwater use should be based on a socio-economic-environmental decision, by relevant stakeholders and authorities, over the conditions at this new dynamic equilibrium. This description of aquifer yields is well established scientifically and referred to as the Capture Principle, and the link to groundwater use sustainability is also well established. However, implementation of the Capture Principle remains incomplete. Water balance type calculations persist, in which sustainability is linked directly to some portion of recharge, and aquifers with high use compared to recharge are considered stressed or over-allocated. Application of the water balance type approach to sustainability may lead to groundwater being underutilised. Implementation of the capture principle is hindered because the approach is intertwined with adaptive management: not all information can be known upfront, the future dynamic equilibrium must be estimated, and management decisions updated as more information is available. This is awkward to regulate. This paper presents a Decision Framework designed to support implementation of the capture principle in groundwater management. The Decision framework combines a collection of various measures. At its centre, it provides an accessible description of the theory underlying the capture principle, and describes the ideal approach for the development operating rules based on a capture principle groundwater assessment. Sustainability indicators are incorporated to guide a groundwater user through the necessary cycles of adaptive management in updating initial estimations of the future dynamic equilibrium. Furthermore, the capture principle approach to sustainable groundwater use requires a socio-economic-environmental decision to be taken by wide relevant stakeholders, and recommendations for a hydrogeologists' contribution to this decision are also provided. Applying the decision framework in several settings highlights that aquifer assessment often lags far behind infrastructure development, and that abstraction often proceeds without an estimation of future impacts, and without qualification of the source of abstracted water, confirming the need for enhanced implementation of the capture principle.
Successful field pilot scale nitrate removal using low technology methods	Sumaya	Israel		2015
Abstract Decades of monitoring, characterising, and assessing nitrate concentration distribution and behaviour in the soil profile and it's pathway into groundwater have resulted in a good understanding of its distribution in the country. While the national distribution is of great importance, site specific conditions determine fate, transport, and ultimately concentration in a specific area. Field experimental work included installation of a barrier containing a cheaply available carbon source to treat groundwater. The "reactor"/ tank with dimensions- 1,37m height, 2.15m diameter used for the experiment was slotted for its entire circumference by marking and grinding through the 5mm thick plastic material. The top section was left open to allow for filling and occasional checking of filled material during the experiment. The tank was packed with Eucalyptus globulus woodchips which was freely available at the site. Concentrations of groundwater nitrate at the site were well over what could be expected in any naturally occurring groundwater systems, and would result only by major anthropogenic activities in unconfined aquifer areas of South Africa. The changes in parameter concentrations with time were measured in order to determine the efficiency and life span of the carbon source used for the experiment. This paper considers 35 months of monitoring at a site where a low technology method was implemented. Field implementation was tested at a site which previously experienced some NH4NO3 spills. Main results from the field work showed that nitrate was totally removed at the treatment zone and surrounding boreholes, and even sulphate and NH4+ were removed during the experiment. This shows that the woodchips were successful in affecting denitrification for 35 months. Data also shows that boreholes further downstream from the tank had reduced NO3-, SO42- and NH4+ levels. Using the available biodegradable carbon for the woodchips based on its composition, a barrier lifespan could be determined. The results of calculations showed that the barrier would be effective for at least another 6.9 years from the period of the last sampling date. A total lifespan of about 10 years can thus be estimated.
Cost Effective Drilling Methods For Obtaining Water Supply In Sodwana, Northern Kwazulu Natal	Jean	Simonis	KwaZulu-Natal	2015
Abstract We contend that borehole drilling costs on the Zululand Coastal Plain, South Africa can be much reduced by assisting low cost drillers in drilling 6" diameter boreholes using light weight, maneuverable rigs with trained teams which are more cost-effective and provide optimal value for money invested over the lifespan of the borehole. The improved drilling package will allow local drillers to tap into the deeper more sustainable aquifer identified in the area and provide for better borehole construction. The remoteness of the rural population in the Maputaland area, northern KZN, South Africa, influences the degree of groundwater development. Rural water supply infrastructure is minimal and 40 per cent of the rural community is forced to rely on surface water as well as shallow, low cost drilling for water supply. A number of these low cost drillers were investigated to determine their expertise. Results showed that formal training in drilling technology is unavailable in the area. The inexperience of the drillers results in poor borehole construction. Currently low cost drilling is not cost effective as most of these boreholes collapse after a short time. The correct method of drilling in the area is by Direct Mud Rotary (DMR). Professional DMR drilling and borehole construction costs are in excess of US$ 125/m, unaffordable for poor households. We propose that with limited training and suitable equipment the local drillers can halve existing drilling costs, provide quality work as well as focus on good management practices. This will create jobs as well solve the pending water crisis in the area (and elsewhere in Africa).
TEMPEST for groundwater exploration	Odirile	Dingoko	Australia	2015	Airborne electromagnetic surveys
Abstract In recent years there has been renewed interested in identifying and understanding groundwater resources. Airborne electromagnetic (AEM) surveys can provide useful, cost effective information about the geometry of aquifers and their host rocks. TEMPEST is a fixed wing AEM system which has been used extensively for groundwater applications. The system possesses many attributes which aid in groundwater exploration including: broad operational bandwidth; multifaceted software approach; and, a distinctive calibration technique. These features allow both shallow and deep subsurface features to be imaged which aid in mapping groundwater aquifers along with the broader groundwater subsystem. This paper will review TEMPEST surveys flown for the Western Australian Department of Water (DoW) for the purpose of groundwater characterisation. The surveys were focussed on the identification of geological contacts, subsurface aquifers and seawater intrusion extents. The survey data was interpreted using an integrated approach which involved reviewing the newly acquired geophysical data, identifying contacts and anomalous features in the acquired data, reviewing existing geological and geophysical data in the area and correlating features identified in acquired data to known geology. The first case study was flown over the North Gnangara area of the Perth Basin with the primary aim of defining the spatial distribution of clay and silty layers that impede recharge to the groundwater table. The survey succeeded in achieving its primary aim of identifying the distribution of clay layer targets. Through the integrated interpretation approach it was also successful in achieving its secondary aims by clearly defining the contact between superficial units and the underlying stratigraphy, identifying key structures within the basin, outlining the top of the seawater intrusion, and mapping confining strata within the deeper aquifer systems in the Perth Basin. The second case study was flown over the lower reaches of four river systems in the North Pilbara coast with the aim of understanding the aquifer geometries and groundwater salinity distribution within the region. The primary aims of the survey were achieved and provided a basement geology map, relative porosity maps, approximate weathered and unweathered bedrock surfaces as well as the approximate geometry of the seawater intrusion within all survey areas. It was also possible to map the interpreted extents of alluvial aquifers within two of the river systems as well as the contact between two sandstone aquifers present in one of the river systems. These case studies show that the TEMPEST AEM system can provide valuable information about the geometry of aquifers and their host geology. AEM surveys should be used as an initial method for determining broad aquifer geometry and the identification of priority areas prior to further less cost effective water bore drilling.
Effects of Urbanization and Agricultural activities on Aquifer storage and Groundwater quality	Athenkosi	Matshini		2015
Abstract POSTER Aquifer stress arising from urbanization and agricultural activities, these two factors affect aquifer properties when prolonged. Increase in urbanization especially those situated on top unconfined or semi-confined aquifer results in pressure on natural resources, this includes water resources, and changes of land use for agricultural purposes with high economic benefits has an effect on groundwater quality to due to application of Nitrogen- fertilizers during crop rotation and this is largely experienced in developing countries. The effects ranges from groundwater quality to aquifer storage as prolonged aquifer withdrawals due to irrigation, construction, manufacturing affects groundwater storage. Assessment of urbanization and agricultural effects on groundwater requires a complex analysis as integration approaches needs to be discovered for a better analysis of the two more specially when assessing groundwater pollution. The study was conducted to assess the impacts of urbanization and agricultural activities on aquifer storage and groundwater quality: by (a) determining the relationship between the occurrence of contamination due to urbanization by assessing contaminants present in the study area (b) develop groundwater protection, and if any offer recommendation for groundwater management. Multiple-well tests were conducted observing the behavior of drawdown and recovery for assessing groundwater storage. Two aquifer properties were observed to yield information about any changes in aquifer storage (transmissivity and storage coefficient) and groundwater quality lab test focusing on TDS, nitrate and pH were conducted. Historical results reflect that before industrial and urban revolution the groundwater contained small amounts of TDS compared with the present results. Increase in nitrate and pH concentrations observed in location closer to agricultural areas. Prolonged aquifer withdrawals increases expansion of cone of depression and therefore increases aquifer vulnerability and the risk of aquifer being polluted, and this increases storage coefficient. This study can be used to formulate protection zones for water resources and practice towards groundwater management.
Groundwater fingerprinting for identifying potential project risks	Meris	Mills		2015
Abstract Implementation of a mining project in South Africa involved dewatering of a fractured rock aquifer at considerable depth below ground level. Groundwater quality within this aquifer is not suitable for domestic use due to high levels of salinity. Numerous geological investigations in the area indicate that the target aquifer is confined, with a different piezometric head to the shallower aquifers. However, regulators and other interested and affected parties expressed concern regarding the potential mixing of more saline groundwater from the deeper aquifer to be dewatered with groundwater from shallower aquifers, which are extensively used for farming and domestic purposes. A large database of groundwater quality monitoring data collected over 16 years was available to investigate the degree of mixing between the deeper more saline and shallower freshwater aquifers. The groundwater chemistry of selected boreholes with known geological profile, depth and construction was used to develop groundwater fingerprinting criteria for each of the aquifers in the area. These fingerprinting criteria were then applied to private and exploration boreholes in the area in order to identify the main aquifer from which groundwater was being sourced. Once the boreholes were classified in terms of groundwater origin, an attempt was made to identify indicators of mixing with deeper, more saline groundwater from the aquifer being dewatered. Groundwater fingerprinting allowed identification of impacts related to the mining operations. The data showed that there was no upward mixing of water related to dewatering operations, but rather that surface spillages and disposal schemes may have resulted in minor changes in shallow groundwater quality. {List only- not presented}
Effects of artefacts other than horizontal groundwater flux on a single-borehole tracer dilution test: Field evidence	Modreck	Gomo		2015
Abstract This article present field evidence on the effect of artefacts other than the horizontal groundwater flux on the single-borehole tracer dilution test. The artefacts on the tracer dilution were observed during two single-borehole tracer dilution tests conducted in an alluvial channel aquifer in the main Karoo Basin of Southern Africa. Field evidence shows that early time of the tracer dilution plot can be affected by artefacts other than the horizontal groundwater flux. These artefacts have great potential to increase the early time gradient of tracer dilution curve leading to overestimation of the horizontal groundwater flux. A qualitative approach that can be used to isolate and remove portion of the dilution plot that has resulted from artefacts other than the groundwater flow prior to calculating the horizontal groundwater flux is proposed.
Numerical model simulation of underground mine to determine reliable groundwater inflow predictions	Brendon	Bredenkamp	Kalahari	2015	predictive simulations, groundwater moddeling system, dewatering measures
Abstract The proposed underground copper mine is one of the first Greenfield developments in the Kalahari Copper Belt. Groundwater resources in the region are scare and saline mainly due to minimal recharge. Management and simulations of groundwater inflows formed an integral part of the new mine design to reduce production losses caused by the inflows and to ensure a safe mining environment. The mine is located is a complex hydrogeological setting characterised by folding and deep water levels. Multiple fractured aquifers are associated with the mining area. Groundwater numerical modelling was performed in Groundwater Modelling System (GMS) using MODFLOW-NWT. Results of the scenarios were used as a management tool to aid in the potential inflow predictive simulations and dewatering management. The numerical model was calibrated by using field measured aquifer parameters and piezometric heads. Numerical simulations assisted in estimating average groundwater inflows at certain stages of the proposed mine development. The simulated mine groundwater inflow volumes were used as input into the design of the dewatering measures to ensure a safe mining environment.
Monitored Natural Attenuation of Inorganic Constituents: A Case Study in a Karoo Aquifer	Vevanya	Naidoo	Karoo	2015
Abstract Natural attenuation describes a set of natural processes which decrease the concentrations and/or mobility of contaminants without human intervention. In order to evaluate and demonstrate the effectiveness of natural attenuation, regular long term monitoring must be implemented. This entire process is called Monitored natural attenuation (MNA). The focus of MNA is generally placed on hydrocarbons and chlorinated solvents but according to the United States Environmental Protection Agency (USEPA) MNA can be used for various metals, radio nuclides and other inorganic contaminants. MNA was deemed the best method to reduce the concentration and mobility of contaminants impacting the groundwater environment, at a fertiliser plant in the Free State. A number of improvements in infrastructure were made in 2013which were assumed to have prevented further release of contaminants into the groundwater system, from the source areas on site. MNA was also considered to be the most effective affordable solution for the site as groundwater in the vicinity is not used for domestic purposes (low risk). Cl, NO3 and NH4 were used to monitor the movement of the contamination off site and the effectiveness of MNA. With regards to the inorganic contaminants emanating from the site, sorption, dispersion, dilution, and volatilization are the main attenuation mechanisms. These mechanisms are considered to be non-destructive attenuation mechanisms. Denitrification, nitrate reduction through microbial processes, may also facilitate in the attenuation of the in organic constituent nitrate. Denitrification is considered a destructive mechanism. Classed posts and temporal graphs of the Cl, NO3 and NH4 concentrations between 2008 and 2014 were utilised to show the movement and change in size and shape of the contamination plumes and subsequently, monitor MNA. The data indicates that the NO3, Cl and NH4 contamination plumes from the various source areas on the site have detached from the site and are currently moving down gradient along the natural drainage. Contaminant concentrations at the site have generally decreased in recent monitoring events while concentrations downstream of the site have remained stable. This indicates that MNA is currently an effective method of remediation for the site and monitoring should be continued to ensure that it remains effective.
3-D electrical conductivity image as a decision-aiding tool in the post-closure management of a South African colliery	Lize	Wessels	Vereniging	2015
Abstract The colliery is situated in the Vereeniging-Sasolburg Coalfield, immediately southwest of Sasolburg in the Republic of South Africa. The stratigraphy of this coal field is typical of the coal-bearing strata of the Karoo Sequence. The succession consists of pre-Karoo rocks (dolomites of the Chuniespoort Group of the Transvaal Sequence) overlain by the Dwyka Formation, followed by the Ecca Group sediments, of which the Vryheid Formation is the coal-bearing horizon. Mainly the lava of the Ventersdorp and Hekpoort Groups underlie the coal. The Karoo Formation is present over the whole area and consists mainly of sandstone, shale and coal of varying thickness. The underground mine was flooded after mining was ceased at the colliery in 2004. The colliery is in the fortunate position that it has a very complete and concise monitoring programme in place and over 200 boreholes were drilled in and around the mine throughout the life of the mine. To stabilise mine workings located beneath main roads in the area, an ashfilling project was undertaken by the colliery since 1999. A key issue is if the mine will eventually decant, and what the quality of the water will be. This is important for the future planning of the company, as this will determine if a water treatment plant is necessary, and what the specifications for such a plant will be, if needed. Therefore it was decided to do a down-the-hole chemical profile of each available and accessible borehole with a multi-parameter probe with the aim of observing any visible stratification. Over 90 boreholes were accessible and chemical profiles were created of them. From the data collected a three - dimensional image was created from the electrical conductivity values at different depths to see if any stratification was visible in the shallow aquifer. The ash-filling operations disturbed the normal aquifer conditions, and this created different pressures than normally expected at a deeper underground colliery. From the three-dimensional image created it was observed that no stratification was visible in the shallow aquifer, which lead to the conclusion that in the event that if decant should occur, the water quality of the decanting water will still be of very good quality unless external factors such as ash-filling activities is introduced. It is not often that it is possible to create chemical profiles of such a large number of boreholes for a single colliery and as a result a very complete and informative three-dimensional electrical conductivity image was created. This image is very helpful in aiding the decision making process in the future management of the colliery and eventually obtaining a closure certificate, and also to determine whether ash-filling is a viable option in discarding the ash.
Waste Management in Nigeria: A paradigm Shift	Akobundu	Amadi	Nigeria	2015	waste management, environmental pollution, Modern sanitary landfill
Abstract The manner in which municipal and industrial wastes generated are disposed in the urban areas in Nigeria is worrisome. The practice of dumping solid wastes in abandoned burrow-pits or valley and the discharge of liquid wastes directly on soils or surface water without any form of treatment has resulted in soil and water pollution. The continuous release of dangerous gases into the atmosphere by industries unabated has contributed to air pollution. These inadequate waste disposal techniques have created serious environmental and health challenges. Due to increasing population growth rate, urbanization, industrialization and economic growth, there has been a phenomenal increase in the volume of wastes generated daily and handling of these wastes have constituted an environmental problem. The need to manage these wastes in an environmentally-friendly manner that will guarantee safety of the soil and water resources lead to the present study. The newly designed waste management landfill incorporates advanced features such as complex multiple liner construction to facilitate organic decomposition and maintain structural integrity. The multiple protective layers and regular monitoring ensure that the waste management landfills exist in harmony with their surrounding environments and communities. These features that enhances maximum protection of soil and water from contamination by plume by decaying waste is lacking in the un-lined open waste dumps been practiced in the country. Pollution abatement, waste reduction, energy saving, health and economic benefits are some of the advantages of the newly designed sanitary landfill system.
Water Monitoring in the Mining Industry: An Overview	Callie	Pickering		2015
Abstract Water monitoring is a key aspect in the mining industry, in terms of gathering baseline data during the pre-construction stage, identifying potential areas of concern and mitigating source pollutants during the operational stage. A proper water monitoring program assists in the monitoring of plume development and water level rebound during the closure phase. The data made available through consistent long term monitoring should not be underestimated. Monitoring the effect that coal mine operations have on the water quality and quantity of surface and groundwater resources is a complex and multidisciplinary task. Numerous methodologies exist for monitoring of this kind. This paper will supply an overview of the water- rock chemistry associated with coal mine environments and the key indicator elements that should be focused on for water monitoring as well a review of the Best Practice Guidelines requirements in terms of water monitoring. Two case studies of coal mines in KwaZulu Natal will be reviewed, the key challenges outlined and mitigation measures implemented. The impact of requirements such as those set out by the Department of Water and Sanitation in terms of strict water quality limits for water containment and waste facilities as specified by Water Use Licences has also created unrealistic non-compliance conditions. The initial approach to creating a water monitoring programme should involve first identifying gaps in previous datasets and delineating potential sources of contamination. The sampling frequency will depend primarily on the water resource being monitored and the water quality analysis will depend on the type of facility. The facilities required for a specific situation will depend on the type and amount of waste generated, potential for leachate formation, vulnerability of groundwater resources and potential for water usage or resource sensitivity.
Contaminant Plume Mapping using Electrical resistivity method in Northern Namibia	Nelda	Breedt	Namibia	2015
Abstract An electrical resistivity geophysical study was conducted at a historically contaminated site in northern Namibia. It is well known that fracture breaks/fault features are often good conduits for water and contaminants, leading to high flow velocities and the fast spread of contaminants in these conduits. The aim of the resistivity survey was to evaluate the preferential flow paths for groundwater and the distribution of contamination in the unsaturated zone and saturated aquifer. The 2-D electrical resistivity imaging survey comprised 12 northeast-southwest trending traverses, with a nominal separation of roughly 200 m with traverse length ranging between 1,000 and 2,000 m and five (5) northwest-southeast trending traverses, with nominal separation of roughly 600 m with traverse length ranging between 900 and 2,400 m. A Wenner and Schlumberger electrode array with a 10 m electrode spacing configuration were employed, allowing for observation depths of about 75 to 80 m below surface. The 2-D electrical resistivity method was successful in discriminating between low and high resistivity subsurface features across the project site. Borehole yields associated with the fault zones were high and confirmed the existence of preferential flow paths. The interpretation of contaminated subsurface areas (low resistivity/high conductive) of the unsaturated zone correlated with historic site activity and infrastructure related to the old return water dam, Old Tailings, plant area and coal stockyard, whereas the spatial distribution of the saturated zone seems to be more focused to the interpreted fracture breaks/fault features associated with the latter three areas. Groundwater quality data showed a good correlation between boreholes with high electrical conductivity and the zones of low electrical resistivity signatures. Preferential flow paths correlated well with interpreted fault zones from gravity data.
A management plan towards the flooding of an opencast mine with adjacent underground sections.	Eelco	Lukas	Mpumalanga	2015
Abstract The colliery is situated in the Mpumalanga Coalfield, north of Trichardt in the Republic of South Africa. The opencast is already rehabilitated but still acts as an entrance to the underground sections of the mine. The Life of Mine indicates active mining until 2035. We were tasked to develop a mine closure plan. Two surface drainage systems are present, namely the Trichardt Spruit and the Steenkool Spruit. Both these systems have been diverted locally around the opencast with the necessary permission, to maximize coal extraction and protect the environment. Several passive treatment options were tabled to minimise the post closure environmental contamination. After careful consideration it was decided to develop a mine flooding plan to exclude oxygen from the mine thereby minimising the sulphate generation inside the opencast and underground sections. To start flooding as early as possible, sections of the underground mine were identified as natural or artificial compartments to store water. The rehabilitated opencast is flooded using recharge water from rainfall. The capacity of the rehabilitated open pit is enlarged to evaporate all the excess water in the pit making the need for a treatment plant unnecessary.
Characterisation of a large LNAPL plume in Limpopo Province, South Africa	Mahlogonolo	Phahlamohlaka	Limpopo	2015
Abstract Work is being conducted in Limpopo province following a large volume spill of petroleum hydrocarbons that took place from a leaking underground pipeline, resulting in significant volume of groundwater contamination. This is by far the largest spillage to date in South Africa.10 million litres of jet fuel leaked for a 15 year period from an underground pipeline until its detection 13 years ago. The leak has since been repaired and bailing was the first method proposed and applied to the recovery of the free product, but due to its ineffectiveness the "quicker"pump-and-treat method replaced it. Due to complications caused by pum-and-treat, the process was stopped in 2007 and is about to be reinstated again in 2013. A village to the north of the spillage depends mostly on groundwater. Immediate remediation actions have to be established before the contaminant reaches their abstraction boreholes. This project aims to model the areal extent of this contaminant and eventually design a life cycle of remediation. This will be based on comparison between existing models dated 2002 and 2012 respectively for background information and to address the influence of ten years' bailing, pumping and natural attenuation. The new model will focus around implementing remedial measures to prevent further migration of the free phase or dissolved plumes in order to protect the water supply to the surrounding villages. The progress will be presented in this paper.
An Acid Base Accounting study of the coal-bearing formations in the Waterberg coalfield	Lore-Mari	Deysel	Karoo	2015	coal mine, sulphur, acid base accounting
Abstract Coal constitutes 77% of the primary energy needs in the country, with the Waterberg Coalfield estimated to host about 40% of the remaining South African coal resources. The Karoo coals were deposited in a reduced environment that have the potential to produce sulphides within the sediments they are hosted. The sulphur content within the coal can range from 0.1 wt.% to as high as 10 wt.%. Mining generates a disturbance in the natural groundwater levels and affects the surrounding water chemistry when sulphate is produced as a result of pyrite oxidation. Acid base accounting (ABA) was used to determine the balance between the acid producing potential (AP) and acid neutralizing potential (NP). From the analysis the Net Neutralising Potential (NNP) classified samples as either acid or non-acid producing. ARD does not only result in the generation of acid but is accompanied by decreased pH and increased values of specific conductance, dissolved metals and sulphate. The ABA results showed that interburden and coal samples have higher risks of producing acid upon oxidation than overburden samples. Higher concentrations of neutralising minerals are present in overburden samples. ABA indicated that the material 60m below ground surface had a higher acid producing potential than the material above. The analysis from kinetic tests showed the long-term behaviour of different samples, with the electrical conductivity (EC) and pH changing over time. Samples with lower pH continued to produce more sulphate, while calcium continued to increase until it was depleted from the samples. Inductively coupled plasma analysis determined the release of the heavy metals which can be detrimental to the environment, such as As, Co, Ni and Pb. The water demand will increase as mining continues in the area, with inter-catchment transfers identified to overcome local water scarcity issues. ARD poses a big threat to both groundwater and surface water resources.
Using gravity anomalies from GRACE to estimate changes in groundwater storage in the Vaal River Basin	Khuliso	Masindi		2015
Abstract The Gravity Recovery and Climate Experiment (GRACE) satellites detect minute temporal variation in the earth's gravitational field at an extraordinary accuracy, in order to make estimation of the total water storage (TWS). GRACE provides a unique opportunity to study and monitor real time water variation in the hydrologic stores (snow, groundwater, surface water and soil moisture) due to increases or decreases in storage. The GRACE monthly TWS data are being used to estimate changes in groundwater storage in the Vaal River Basin for a period (2002 to 2014). The Vaal River Basin has been selected, because it is one of the most water stressed catchments in South Africa; it is well-renowned for its high concentration of industrial activities and urbanized zones. Therefore, in order to meet future water demands, it is critical to monitor and calculate changes in groundwater storages as an important aspect of water management, where such a resource is a key to economic development and social development. Previous studies in the Vaal River Basin were mostly localised focusing mainly on groundwater quality and to a lesser extent groundwater assessment. Hydrological models have been generated for the whole of South Africa, but many of these models do not take into account the groundwater component. Thus, there is a significant gap in the understanding of surface and ground water dynamics in the Vaal River Basin. The paucity of data and monitoring networks are often the limitation in calculating changes in water storage over a large area, particularly in Africa. In this scenario GRACE is a good approach to estimate changes in hydrological storages as it covers large areas and generates real time data. It does not require information on soil moisture, which is often difficult to measure. The accuracy of calculating change in groundwater storage lies in the processing of GRACE data and smoothing radii. For this study, smoothing radii of 1500, 900, 500, 300, 150 and 1 km are used. Currently the associated error with different smoothing radii is unknown. The preliminary results indicate that the study area experienced a loss in TWS of -31.58 mm equivalent water height over a period of 144 months in TWS at 300 km smoothing radius. The change in groundwater storage is calculated by incorporating hydrologic components to the TWS (work in progress). The results obtained from this study will be compared to existing hydrological models and results generated from models applicable to the semi-arid region of South Africa. It is anticipated that this satellite observation technique, GRACE, will provide an accurate estimate of change in groundwater storage. Furthermore, it will show the usefulness of satellite based techniques for improving our understanding of groundwater dynamics, which will improve water management practices.
Radon-222 in Thermal Springs of Limpopo Province, South Africa	Humberto	Saeze	Limpopo	2015
Abstract Studies have shown that the use of natural water (drinking and bathing) with high level of 222Rn concentration may contribute to negative health effect in human beings. Thermal springs located in Limpopo province were sampled for the determination of 222Rn concentration by gamma ray spectrometry. The spring water has been used for domestic purposes: drinking and bathing, and for recreation bathing mainly. 19 samples were collected between thermal springs emanation points and swimming facilities (out and in doors). Radon-222 concentration found in these water ranges from 0.2 to 624 Bq/l. These results indicate that 7 thermal springs may represent increasing risk on bathing or inhalation of radon gas, leading to an increased risk of healthy.
Numerical groundwater flow model for the Palla Road wellfield, Botswana	Martin	Holland	Botswana	2013	numerical groundwater flow model
Abstract The Palla Road well-field is located in the Central District of Botswana approximately 160 km from Gaborone and 50 km from Mahalapye. The aim of this project was to review and update the existing groundwater model developed in the late 1990s of the Palla Road well-field in order to assess the viability of long-term groundwater abstraction due to the increasing water demands in the region. The main hydrogeological units recognised in the project area comprise of aquifer systems developed in the Ntane Sandstone Formation and formations of the Middle Ecca Group with minor aquifers developed in Mosolotsane Formation and the Stormberg Basalt. The finite-difference model boundary covers an area of 3 702 km2 and was set-up as a three-dimensional semi-uniform grid comprising of four layers. Eight recharge and 14 hydraulic conductivity zones in accordance with the geological model were distinguished. Steady state calibration was accomplished by varying the hydraulic conductivity values, while keeping the recharge rates constant in order to achieve a unique solution. Transient calibration of the model covered three larger stress periods namely: (1) initial condition (pre-1988), (2) abstraction period (1988 to 2012) and (3) predicted model simulations (2013 to 2036). The calibrated groundwater flow model was used to assess the impacts associated with the proposed abstraction scenarios for the Palla Road and Chepete well-fields with consideration of potential cumulative impacts due to the Kudumatse well-field. Three basic scenarios comprising certain sub-scenarios based on the future water demand for the Palla Road and Kudumatse region were considered. The model simulations show that the abstraction scenario 2a, namely simultaneous abstractions from the Chepete/Palla Road and Kudumatse well-fields, poses a risk to the sustainability of downstream water resources. The maximum simulated drawdown in the central and southern parts of the Palla Road well-field reach 14 m after six years of pumping. Although outflow diminishes after a six-year period, it is restored to approximately 80-90% after the simulated recovery period. The presented 3-D multi-layer model can be used as a tool to determine the optimal abstraction rates while giving cognisance to the sustainability of the resource.
Potential Impacts Of Fracking On Groundwater In The Karoo Basin Of South Africa	Gerrit	Van Tonder	Karoo	2013	potential impact
Abstract Determining impacts associated with the production of shale gas in the semi-arid Karoo on groundwater is vital to people living in the Karoo. On the one hand shale gas can be a game-changer for energy supply, but on the other it may have a devastating effect on the environment. Knowing the potential impacts of shale gas mining beforehand, the government can set appropriate regulatory protocols and tools in place to mitigate potential risks. This paper describes research done on the potential impact that hydraulic fracturing could have on groundwater in the Karoo. A wild card that only exists in the Karoo Basin of South Africa is the numerous dolerite intrusions. These dolerite structures are associated with relative high-yielding boreholes because of the fractured contact aureole that exist between solid dolerite and the adjacent Karoo sediments. Compromised cement annuli of gas wells are the major preferential flow paths along which methane and fracking fluid can escape into shallow, freshwater aquifers. This study focused solely on the impact of compromised cement annuli of gas wells. The Karoo Basin is under artesian conditions which imply that any pollutant will always try to migrate upwards in the Karoo. The hot-water springs in the Karoo indicate that upward velocities of water are relatively high (the spring water take only days to travel from deep down to the surface). The cubic law was used to estimate potential upward leakage rates from gas wells (during production, but after cessation thereof as well, when pressures will rebuild because of artesian behaviour of the Karoo formations). Potential leakage rates along faulty annuli of a well can vary between a value close to zero to two liters per second in the case of an aperture of 0,5 mm. These leakage rates were used as input to a 2D numerical groundwater flow and mass transport model. The 2D model was run for 30 years and the movement of pollution from the gas wells on the pad simulated. The model indicates that an area of 300 ha could be contaminated over a period of 30 years in a downstream groundwater flow direction. If an abstraction borehole drilled along a fault zone or a dyke, intersecting the fracked reservoir, is introduced into the model, results predict that the pollutant will reach the borehole in less than two months if the borehole is situated six kilometres from the well-pad. The total impact that fracking will have on the groundwater in the Karoo, is a function of the total area that will be fracked. The outcomes of this research clearly show that fracking in South Africa cannot be done in the same way than it is currently done worldwide. A rule that will force gas companies to disclose fracking fluid contents is non-negotiable. Companies should also be required to measure pressures in the fracked gas reservoir after closure. An additional requirement to enforce sealing of the entire fracked reservoir with a very dense material like bentonite or a mud with a very high density to capture the fracking fluids deep down in the gas reservoir should not be negotiable.
Investigation Of Possible Contaminant Plumes Emanating From Residual Mine Deposits In The Mpumalanga Province Of South Africa, Results From Geophysical Surveys	Emmanuel	Sakala	Mpumalanga	2013	contamination, plumes, geophysical methods
Abstract Acid-mine drainage (AMD) has received considerable media coverage in South Africa as of late. This have caused a considerable increase in researches, most of them with emphasis on decanting of contaminated water from the old gold mines in Witwatersrand basins and fewer on mine residue contamination from coal and gold mines in the Mpumalanga Province. The paper outlines results of ground geophysical surveys that were carried out along the perimeter of two mine residual deposits (dumps) in the Barberton Greenstone Belt, Mpumalanga Province. The aim of the study was to generate a 3D geoelectric model of the subsurface showing possible acid-mine drainage contaminant pathways. Two geophysical methods, namely Frequency Domain Electromagnetic Profiling (FDEM) and Electrical Resistivity Tomography (ERT) were applied in order to investigate the variation of electrical conductivity in the subsurface. The ERT method was done over frequency domain electromagnetics anomalies. FDEM electrical conductivity values ranging between 40 mS/m to 60 mS/m were considered as anomalous in that geological terrain. These areas were then surveyed by the ERT method to check the depth extent of these FDEM anomalies. On the resistivity section, between station 40 m and 80 m of Dump 1 – ERT1, a discontinuity in the bedrock was identified. The area could act as a pathway for contaminants to flow from the dump to groundwater. The FDEM survey identified an area with high conductivity values to the north of Dump 1. The ERT results also showed a shallow plume at 30 m depth which is consistent on two parallel sections on Dump 1. The area could be a possible AMD pathway of a mine dump residue to a Komati tributary on the north. The bedrock is generally characterised by high resistivity values; a break in the bedrock exists on this high resistivity zone on ERT 6. This break could be a fault zone which can act as possible pathway of (AMD) from a mine dump residue to a shallow aquifer. Potential contaminant recharge pathways were delineated using geophysical, electrical and electromagnetic methods. Potential groundwater recharge pathways and sub-vertical low resistivity zones with values <100Ohm.m were delineated using the ERT method. Investigation of contaminant plume migration is recommended over the anomalies that were generated from geophysics data in the Barberton areas. New technologies (artificial neural networks (ANN), fuzzy logic, etc.) combined with laboratory studies is recommended for development of a software platform that accepts 3D geoelectric data (present study), constrained with geology, geochemistry (soil and water), hydrology and hydrogeology data.
Modelling Of Impacts Of Fracking On The Karoo Groundwater Systems	Jennifer-lee	Pretorius	The Karoo	2013	Fracking
Abstract POSTER Hydraulic fracturing, also known as hydrofracking or fracking, is being engaged in the Karoo region of South Africa in order to enhance energy supplies and improve the economic sector. It will also lead to independence in terms of reduced amount of imports for fuel due to an estimated 13.7 trillion cubic metres of technically recoverable shale-gas reserves in South Africa. Fracking is an extraction technique used with the purpose of having access to alternative natural methane gas, which is interbedded in shale deposits deep under the surface of the earth. In this process boreholes are drilled horizontally into shale formations to cover a larger area in the shale and subsequently attain more natural gas. After these horizontal boreholes are drilled, large volumes of water, mixed with chemicals and sand, are pumped into these boreholes under a very high pressure, forcing the natural gas out. This water mixture is referred to as the fracking fluid. Water is the main component in the fracking fluid and the water used for the fluid reaches volumes up to 30 million litres per borehole. The aim of this study is to present a baseline study of the area and its water resources to ultimately facilitate in resolving the actual impact hydraulic fracturing will have in the area, using a simulation model which will predict the migration of the fracking fluid in the subsurface. In this model, the chemistry of the fracking fluid will be included to determine the impact it might have on the groundwater quality in the area
Arsenic In The West-African Water Reserves: Investigation Into Sources Of The Contaminant Through Case Studies In The Region	Andre	van Coller	Western Africa	2013	Contaminant, investigations, Groundwater reserve
Abstract The mineral-rich basin of the West African region has vast reserves of gold, diamond as well as iron ore deposits. Throughout the regional geological setting characterised by structural variations and intrusive belts with metamorphic mineral-rich sequences covered by saprolite soils, one common chemical constituent remains a constant in the water reserves. Arsenic is in high concentrations throughout the region with chemical ranges commonly above the various country guidelines as well as international IFC and WHO standards. The aqueous chemical species is associated with arsenopyrite-rich mineralogy of the regional greenstone belts and highly weathered soils. This conference presentation investigates the natural source of the arsenic through baseline data, as well as the effect of mining on the already high concentrations of arsenic in both the groundwater and surface water. Natural levels of various chemical species in the regional area are already high at baseline level. One of the main research questions is thus whether mining and other anthropogenic activities will have an impact on the environment or will the changes to concentrations be so insignificant to allow the ecosystems and water users to continue in their current ways without any effect. Various case studies in Burkina Faso, Liberia, Sierra Leone and other countries have been combined to investigate the arsenic-rich resources of the West African region through groundwater specialist investigative methods with emphasis on geochemical modelling of the fluid–rock and fluid–fluid interactions leading to the aqueous chemical conditions in the region.
Witwatersrand Mine Voids – Their Hydrochemistry And Hydrodynamic Characteristics	Eddie	van Wyk	Witwatersrand	2013	Hydrochemistry, hydrodynamics
Abstract Gold mining on the Witwatersrand has started in the late nineteenth century as sporadic open cast mining and ceased in the late twentieth century, leaving a complex network of haulages, tunnels and ultra-deep vertical shafts/sub-vertical shafts. At least three ore bodies (conglomeritic horizons) were mined down to a depth in excess of 3 000 m from surface. Three large mining basins resulted from the mining methodology applied, namely the Western, Central and Eastern (Rand) Basins. In the early days of mining on the Witwatersrand reefs, gold mine companies realised that dewatering of their mine workings is required to secure mining operations at deeper levels and decades of pumping and treatment of pumped mine water followed. As the majority of deep gold mines on the Witwatersrand ceased operations since 1970, the deeper portions of the mine voids became flooded and led to a new era in the mining history in the Witwatersrand. Rewatering of the mine voids is a combination between excessive surface water ingress generated by surface runoff, and to lesser degree recharge from an overlying fractured and weathered aquifer system (where developed). The flow regime in the mine voids from a scattering of ingress/direct recharge points and single discharge points are complex and is driven by shallow (<100 m) and probably deep (>1 000 m) man-made preferential pathways. The high concentrations of iron sulphide minerals (pyrite. for example FeS2) content, three percent (by weight), of the mined reefs/backfilled stopes and surrounding waste rock piles/tailings dams mobilised significant levels of sulphates (SO4) and ferrous iron (Fe2+) producing an acidic mine-void water (<3 pH). Monitoring of the rewatering mine void hydrological regime became necessary following the first acid-mine water decant from a borehole in the West Rand Basin, and the Department initiated a mine-void water table elevation trend and water quality monitoring programme. Results from this monitoring programme will be illustrated and discussed in this paper with some views on the future water quality and discharge scenarios.
Hydrogeology Of Cedarville Flat Primary Aquifer	Nwabisa	Ndlovu	Cedarville, Eastern Cape	2013	Hydrogeology, aquifer, Groundwater, development, hydrogeological conceptual model
Abstract POSTER The study focuses on the primary aquifer in the Cedarville flats. Groundwater extracted from the aquifer is the primary source for domestic and agricultural purposes for farmers and the community in the Cedarville area. The aim of the study is to develop a conceptual hydrogeological model of the primary aquifer in Cedarville flats which may be used as an input to a groundwater flow model that will predict the behaviour of the aquifer. The main objectives of the research are: Characterise the aquifer based on borehole log information, depth to water, hydraulic properties of the aquifer and recharge. Examine the hydrochemistry and environmental isotope composition of groundwater. Develop a conceptual hydrogeological model for the Cedarville primary aquifer. The study area boundary covers a large area including towns like New Amalfi and it goes to Lehlohonolo, but the main focus is in the primary aquifer in the Cedarville flats. The topography varies from predominantly hilly around the escarpment with numerous rivers draining deep valleys to a less mountainous undulating central area like Cedarville flats. Cedarville flats found in the midst of extremely broken ground forming the only considerable extent of plane country in the Eastern Cape territories. They cover about roughly 90 square miles and are hemmed in by ranges of mountains on the south and east and by small hills on the west and north. The aquifer is recharged by Mzimvubu River, which is the largest river in the Mzimvubu river basin; it extends from the Lesotho highlands to the Indian Ocean. It has four main tributaries: the Tsitsa, Tina, Kinira and Mzintlava, all having their headwater in the Drakensberg Mountains. The study area only shows the Tswerika, Riet, Mvenyane, Droewing and non-perennial streams. These streams all flow into the Mzimvubu River and their headwater is from the smaller mountains around the area. The local geology of the area is formed by the Beaufort Group rocks and alluvium rocks which are quaternary in age. The geology that is specifically found in the Cedarville flats aquifer is made of alluvial deposits consisting of clay, sand and gravel. Surrounding the aquifer are Tarkastad subgroup rocks which are predominantly argillaceous rocks, including shale, carbonaceous shale, clay stone, mudstone and siltstone. The primary aquifer in the Cedarville flats is capable of sustaining long-term, large-scale production, and these kinds of aquifers are rarely found in the southern Karoo Basin. Existing boreholes will be used to examine the bore log information, like lithology and thickness of the rocks that form the aquifer. Groundwater hydrographs will be drawn to determine the groundwater level variation. Pumping tests will be conducted to help with hydraulic conductivity, storativity and transmissivity of the aquifer. Water samples will be collected to test the water chemistry and environmental isotopes of the groundwater. Secondary data will be requested from National Groundwater Archives (NGA), Weather SA and the Department of Water Affairs. When all the data is collected, then a conceptual hydrogeological model will be produced.
Characterisation Of Hydrochemical Facies And Water Quality Of The Coastal Plain-Sand Aquifers Of Parts Of Eastern Niger Delta, Nigeria	Akobundu	Amadi	Nigeria	2013	hydrochemical, Water quality, coastal aquifers
Abstract Soil and water pollution are major environmental problem facing many coastal regions of the world due to high population, urbanisation and industrialisation. The hydrofacies and water quality of the coastal plain-sand of part of Eastern Niger-Delta, Nigeria, was investigated in this study. Hydrogeological investigations show that the aquifers in the area are largely unconfined sands with intercalations of gravels, clay and shale which are discontinuous and, however, form semi-confined aquifers in some locations. Pumping test results show that the transmissivity ranged between 152.0 m2/day and 2 835.0 m2/day with an average value of 1 026.0 m2/day, while the specific capacity varied between 828.0 m3/day and 15 314.0 m3/day with a mean value of 6 258.0 m3/day. Well-discharge ranged between 1 624.0 m3/day and 7 216.0 m3/day with an average value of 3 218.0 m3/day, while hydraulic conductivity varied between 3.2 m/day and 478.4 m/d with a mean value of 98.6 m/day. These findings indicate that the aquifer in the area is porous, permeable and prolific. The observed wide ranges and high standard deviations and mean in the geochemical data are evidence that there are substantial differences in the quality/composition of the groundwater within the study area. The plot of the major cations and anions on Piper, Durov, and Scholler diagrams indicated six hydrochemical facies in the area: Na-Cl, Ca-Mg-HCO3, Na-Ca-SO4, Ca-Mg-Cl, Na-Fe-Cl and Na-Fe-Cl-NO3. Heavy metal enrichment index revealed 12 elements in the decreasing order of: Fe > Ni > Cu > Zn > Mn > Cd > V > Co > Pb > Cr > As > Hg. The study identified salt intrusion, high iron content, acid-rain, hydrocarbon pollution, use of agrochemicals, industrial effluents and poor sanitation as contributors to the soil and water deterioration in the area. Saltwater–freshwater interface occurs between 5 m to 185 m, while iron-rich water is found between 20 m to 175 m. The first two factors are natural phenomenon due to the proximity of the aquifer to the ocean and probably downward leaching of marcasite contained in the overlying lithology into the shallow water table, while the last four factors are results of various anthropogenic activities domiciled in the area. The DRASTICA model, a modification of the DRASTIC model, was developed and used in the construction of the aquifer vulnerability map of the area. Modern sanitary landfill that ensures adequate protection for the soil and groundwater was designed and recommended to replace the existing open-dumpsites. Owing to the monumental and devastating effects of hydrocarbon pollution in the area, the need to eradicate gas-flaring and minimise oil spills in the area was advocated. Bioremediation and phytoremediation techniques were recommended to be applied in the clean-up of soils and water contaminated with hydrocarbon in the area.
Southern African Pre-Cretaceous Deep Groundwater Flow Regimes: Evidence And Drivers	Eddie	Van Wyk	South Africa, Botswana, Namibia	2013	groundwater flow, deep drilling
Abstract After drilling technology improvements in South Africa in the early 1900s, several deep (>300 m) exploratory drilling programmes were conducted to explore for pressurised groundwater resources. The results were not significant, except for the Cretaceous Uitenhage Artesian Basin and recent investigations in folded Table Mountain Group Aquifer systems. Large sedimentary units in Southern Africa do have the structural geometry to drive regional artesian systems; however, diverse climate and aquifer hydraulic limitations counteract these conditions to such a level that sustainable basin- like deep flow mechanisms are probably non-existing, except where enhanced by deep mining activities. On the contrary, several deep drilling projects in South Africa, Botswana and Namibia have undoubtedly proven the existence of pressurised groundwater strikes below 300 m (northern Kalahari) to as deep as 3 000 m (western Karoo Basin). Given the regional hydrogeological characteristics of these systems, the availability of sufficient recharge zones required to drive sustainable artesian flow or semiartesian conditions becomes a challenge. The existence of isolated pressurised compartments as a result of the lithostatic pressurisation in the deeper sections of many of the sedimentary successions may prove to be a more realistic explanation for these pressurised water strikes observed during deep drilling operations in Southern Africa.
Flowing Fluid Electrical Conductivity Profiling – An Inventive And Cost-Effective Alternative To Conventional Downhole Hydraulic Profiling Techniques	Samuel D	Möhr	National	2013	Electrical conductivity, Hydraulic profiling
Abstract Flowing fluid electrical conductivity (FFEC) profiling provides a simple and inexpensive way to characterise a borehole with regards to the vertical location of transmissive zones, the hydraulic properties of the various transmissive zones and the intra-well flow conditions which may be present in the well under ambient conditions. The method essentially involves analysing the time evolution of fluid electrical conductivities in a borehole under pumped and ambient conditions using a down-hole conductivity/temperature data logger. The premise of the method is that the borehole column of water has its electrical conductivity altered by adding saline water into the borehole. This results in a contrast in electrical conductivity (EC) between the water in the borehole and the water in the adjacent formation. At depths where transmissive zones are present, decreases in EC values in the FFEC profile will be observed where formation water with a lower EC (relative to the borehole water column) enters into the well, whilst pumping at low abstraction rates (between 500 ml and 1 liter per minute). By altering the EC of the well-borewater and maintaining a constant pumping rate, the sequence of FFEC profiles depicts the dynamic flow and transport response which is dependent upon the hydraulic properties of the formation. In this paper the authors present several examples where FFEC profiling has been used to identify transmissive zones in boreholes where no information existed with regards to the vertical distribution of transmissive zones. Furthermore, the authors present case studies where FFEC profiling has been employed as an alternative technology to more conventional hydraulic profiling techniques. This includes a comparative technology case study where down-hole impeller flow meter technology was employed in addition to FFEC profiling and a multi-rate FFEC profile test which was used to determine discrete fracture transmissivity values in a borehole where packer testing equipment could not be installed. Within the context of groundwater contamination investigations, the method holds several attractions as it generates minimal waste water to be managed and disposed of, is inexpensive and can be completed within a relatively short time period.
The Thermal Springs Of Swaziland – A Review	Nicholas	Robins	Swaziland	2013	thermal springs, hydrochemical
Abstract The thermal springs of Swaziland and adjacent KwaZulu-Natal have, over the years, attracted attention from hydrogeologists, hydrochemists and structural geologists. While some of the springs in Swaziland are well known amenities, others are less well-visited and some difficult to access. There are eleven warm springs in Swaziland, discharging between 1 and 10 l/s from Precambrian age rocks; all are situated at or near valley bottoms. The springs have surface discharge temperatures of between 25 and 52 oC and total dissolved solids concentrations of less than 400 mg/l. In all cases the water is meteoric in origin. Geothermometry indicates that maximum temperatures up to 100 oC are achieved during circulation. If the average geothermal gradient is about 20 oC/km as recorded in a deep mine at Barberton, then this would require circulation up to a depth of several kilometres. However, it is likely that circulation bottoms at about 1 km, as pressure of overburden inhibits dilation of fractures at such depths, and the excess temperature may derive from a locally enhanced geothermal gradient. The discharge water is young, with 14C ages of between 4 000 and 5 000 years.
An Evaluation Of The Physical Parameters That Affect Evaporation Rates On Multi-Component Hyper-Saline Effluents In A Controlled Environment	D	Bent	National	2013	Evaporation rates, Hyper-Saline Effluents, Controlled environment
Abstract The effluent at the eMalahleni water reclamation plant is being processed through reverse osmosis which improves the quality of the mine water to potable standards. Brine ponds are generally used for inland brine disposal and this option has been selected for the eMalahleni plant. Limited capacity to store the brines requires enhanced evaporation rates and increased efficiency of the ponds. This study aims to establish the physical behaviour of the brine from the eMalahleni plant in an artificial evaporation environment. This includes the actual brine and synthetic salts based on the major components. An experimental unit was designed to accommodate and manipulate the parameters that affect the evaporation rate of brines and distilled water under certain scenarios. Two containers, the one filled with 0.5M of NaCl and the other with distilled water were subjected to the same environmental conditions in each experimental cycle. Each container had an area of a 0.25 m² and was fitted with identical sensors and datalogger to record the parameter changes. The energy input was provided by infra-red lights and wind-aided electrical fans. This equipment used in these experiments was to simulate actual physical environmental conditions. The rate of evaporation was expected to be a function of humidity, wind, radiation, salinity and temperature. The experiments showed the type of salt and thermo-stratification of the pond to be significant contributors to the evaporation rate. The results also showed that the NaCl solution absorbed more heat than the water system. The difference in evaporation observed was ascribed to a difference in the heat transfer rate, which resulted in a higher temperature overall in the brine container than in the water container under similar applied conditions. This effect remained despite the introduction of 2 m/s wind flow over the tanks as an additional parameter. The wind factor seemed to delay evaporation due to its chilling effect upon the upper layers of the ponds, initially hindering the effective transfer of radiative heat into the ponds.
Effects Of Dolerite Intrusions On The Geohydrology Of Upper Karoo Sediments In The Elundini Area, South Africa	J	Prinsloo	The Elundini Area, South Africa	2013	Dolerite Intrusions, Geohydrology, Groundwater
Abstract The Karoo Supergroup has a hydrogeological regime which is largely controlled by Jurassic dolerite dyke and sill complexes. The study area is located in the north-eastern interior of the Eastern Cape Province, close to the Lesotho border. The sedimentary rocks of the upper Karoo constitute fractured and intergranular aquifers, due to relatively hydro-conductive lithologies. The main groundwater production targets within the upper-Karoo are related to dolerite intrusions that have a number of characteristics that influence groundwater storage and dynamics. Magnetic, electromagnetic and electrical resistivity geophysical techniques are used to determine the different physical characteristics of the dolerite intrusions, such as size, orientation and the level of weathering. Trends in the data collected from a large-scale development programme can provide evidence that intrusion characteristics also play a role in determining the hydrogeological characteristics of the area. Interpreted geophysical borehole drilling, aquifer testing and water chemistry data can be used to indicate hydrogeological differences between dolerite intrusion types. Observed trends could be used for more accurate future well-field target areas and development.
Hydrogeological Characterisation Of The Fountains East And Fountains West Karst Aquifer Compartments	Vevanya	Naidoo	Gauteng	2013	fountains
Abstract The Fountains East and Fountains West groundwater compartments (by means of the Upper and Lower Fountain springs) have been supplying the City of Pretoria with water since its founding in 1855. These adjacent compartments which are underlain by the Malmani dolomites of the Chuniespoort Group are separated by the Pretoria syenite dyke and are bounded to the north by the rocks of the Pretoria Group (Timeball Hill Formation). Inorganic chemistry data (2007-2012), as well as spring discharge volumes (2011-2012) for the Upper and Lower Fountain springs, supplied by the City of Tshwane Municipality, is being used to characterise the two compartments. This is done by means of piper diagrams, bar graphs and temporal plots. Interpretation of the combined chemical and discharge volume data as well as geotechnical and isotope data (in progress) will aid in understanding the karst aquifer and the controls on groundwater system within and possibly between these compartments.
Hydrogeochemical Footprint As A Result Of Mining Activities In The Johannesburg Area	Tamiru	Abiye	Johannesburg	2013	hydrochemical
Abstract The water quality in the crystalline rocks of the Johannesburg and its environs has been severely altered by the mining activity. Due to freshwater scarcity and dependency of the people on the groundwater, it is important to understand the extent of hydrogeochemical footprint in the area. The water quality characteristic has been thoroughly assessed in the crystalline aquifers based on the input from hydrogeochemical characteristics and environmental isotopes. The results show that the calculated dilution factor for acid-mine decant is in the range of 68% as a result of interaction with surrounding fresh water. The SO4/Cl ratio has a wide range of values that falls between 0 and 306.37, while that of Fe/Ca ratio falls between 0 and 5.59. High SO4/Cl values potentially indicate the interference of acid-mine decant with the groundwater system traced through sulphate concentration. Similarly, a high Fe/Ca ratio also indicates the impact of acid-mine decant on the groundwater system where iron is traced with respect to calcium concentration. In this regard the ratios above 0,25 (with the assumption of 1 to 4 natural abundance for Fe:Ca in water in the area) could potentially represent acid-mine decant source.The results confirm that most of the water- supply wells have heterogeneous chemistry with distinctive hydrogeochemical footprint represented by abnormally high Fe, SO4 and Si as a result of acid-mine decant.