Groundwater contamination as a result of Light Non Aqueous Phase Liquid (LNAPL) releases into the subsurface is a widespread occurrence across South Africa which threatens current and future water resources within the country. Groundwater contaminant fate and transport modelling are common elements of hydrogeological investigations and remedial design methodologies in many developed countries where the models are use as management and decision making tools. In South Africa this is not the case, with contaminant flow and transport modelling rarely being employed as part of LNAPL contamination investigations. Over the last 3 years the Beaufort West study area has had extensive investigative work carried with regards to the determination and delineation of LNAPL related groundwater contaminant plumes which are present underneath a significant portion of the town. As a result an extensive data set has been generated with regards to aquifer geometry, fracture network distribution, aquifer parameters and contaminant plume concentrations and extent. The dataset should in theory provide an opportunity to construct a groundwater contaminant fate and transport model for the area as a remedial management tool. By means of collating previously existing data through a comprehensive desktop study, and supplementing this data with a toolkit of field investigations techniques such as diamond barrel core drilling, percussion drilling, electrical conductivity profiling, fluid electrical conductivity profiling, aquifer pump testing, and low flow inorganic and organic groundwater sampling, the conceptual model of the study area was updated and refined to a point where feasibility of constructing a groundwater contaminant fate and transport model could be assessed. Based upon the conceptual understanding of the study area as defined in the conceptual model developed in the study, a groundwater contaminant fate and transport model is not considered feasible for the study area with body of data currently available. This is attributed mainly to the high level of complexity of the observed natural environment and the challenges in acquiring acceptable quality field data such as aquifer parameters given the uncontrolled pumping environment which is present due to the high number of private groundwater users. Potentially an even greater detractor to the construction of a model, is that considering the conceptual understanding of the study area, there are very few questions of significance whose answers could be provided by a model, and this would indicate that a model would not be an effective remedial management or decision making tool in the current scenario.

The fertilizer production facility had a negative impact on the soil, groundwater and surface water environment due to the handling / storage and production activities at the site. Observations and numerical modelling found the fertilizer product loadings areas as the main source area of contaminants viz. Ca, Mg, NO3, Cl, SO4, EC and TDS. Uncontrolled run-off emanating from the site is a major contributing factor to contaminating the groundwater and surface water resources. A distinct difference could be observed between the geochemical signature of the potential contaminated seepage and that of the groundwater. This geochemical characterisation of the contaminant plume identified an interaction of the leachate and the soil with a high clay (montmorillonite) content, with various cation exchange and sorption processes occurring. Potassium is largely exchanged (for sodium), while phosphates are likely to sorbed on the clay particles. Nitrate is likely to be retarded to a limited extent, especially when redox conditions are conducive to the conservation of the nitrate specie. The elevated contaminant concentrations pose a health risk to potential users and livestock which may ingest the water, especially nitrate concentrations. Numerical modelling was used to validate and develop the site conceptual model. Iterative modelling improved the initial correlation R2 of modelled and observed nitrate concentrations, the correlation improved from 0.29 to 0.64. The model was validated by assuming that horizontal and bedding plan fractures are likely to play a role in contaminant transport (which was not modelled). Artificial recharge (seepage and leachate infiltration) was present at the plant area. Groundwater abstraction from farmers boreholes downstream had an influence on the development of the nitrate plume. Surface water contamination contributed to the current plume geometry and therefore partly responsible for the current plume extent. A secondary groundwater contaminant source was found in the south western part of the study area. Predictive modelling found abstraction of groundwater from site to be the most effective containment measure when compared to a cut-off trench. The groundwater contamination is likely to pose a low current and future risk to groundwater users, as no current groundwater users are found in proximity to the site and the contaminant plume. However a potential surface contaminant risk does occur to down stream surface water bodies during a flood event.

The Waterberg coalfields represent the last area in South Africa, which contain large quantities of coal resources. According to Dreyer (pers. comm. 2009) the Waterberg coalfields contain nearly 50% of the remaining coal resources of South Africa. Given the great demand for coal both local and abroad, primarily to be used as a fuel source for the power generation, the Waterberg coalfields have been targeted for large scale developments in order to exploit the coal. The primary method for exploiting coal is through mining. Mining, in any setting and any location has a diverse and often very serious impact on the environment. A scoping level study was under taken in order to determine the effect the mines will have on the groundwater resources and the pre-mining conditions of the aquifers and the quality of the groundwater. At present there is one operational colliery in the study area, the Grootegeluk mine. This mine has been in operation since the 1980âs and has had a well planned and operated monitoring system in place since the beginning of mining operations. This mine was used as a model to determine the impact new mines will have on the area. From the investigations it became apparent that the coalfield is situated in the Karoo Supergroup geology with the Mokolian Supergroup being represented in the study area by the Waterberg group quartzites. The coalfield is delineated by three major geological structures, the Daarby-, Eezaamheid- and the Zoetfontein faults. With the Daarby- and Eenzaamheid faults being impermeable according to Dreyer (pers. comm. 2009), The Daary fault serves to divide the study area into an area west of the fault with shallow coal and an area east of the fault with deeper coal. Only the shallow coal will be mined. According to Dreyer (pers. comm. 2009), all of the planned infrastructure for the new mines will be located on the Waterberg group rocks south of the Eenzaamheid fault or on the Karoo rocks east of the Daarby fault. To determine the impact the mines would have on the groundwater of the study area, aquifer parameter testing (pumping test and slug tests), water quality determinations (inductively coupled spectrometry), acid-base accounting and numerical modelling were conducted. The results of the aquifer testing indicated low yielding aquifers with the harmonic mean of the transmissivities indicating a low transmissivity of 0.4 m2/d. In addition the recharge for the study area was calculated by means of the Cl and E.A.R.T.H. methods, resulting a value of 1.5% for the area. The average water level for the area was found to be approximately 28 m. The water quality determinations for areas that had not been affected by mining, indicated waters that had high EC values, near neautral pH value and medium to high Cl and sulphate values. The areas that have been affected by activities such as power generation and mining, displayed higher EC, Cl, and sulphate values than the unaffected areas. To more accurately determine the impact the mines would have on the area, numerical modelling was done. Three scenarios were simulated using similar parameters to determine the expected inflow into the mines and whether the mines would ever decant. The results indicated that the worst possible scenario there was an influx varying between 755 m3/d and 1283 m3/d depending on the location of the pits. For the decant models, 50 years after mining had stopped there was a rise of 3 m in the pits themselves. With the pits being simulated being 110 m deep it is concluded that the mines in the area will never decant. The results of the project indicate that the addition of new mines to the area will have an effect on the groundwater quality and quantity and steps should be taken to minimise this as much as possible.

The Kombat Aquifer, as investigated in this study, comprises the dolomite of the upper and lower Otavi Group, encompassing a radius of about 10 km around Kombat Mine. Groundwater flow controls, structural influence, and hydraulic behavior of the groundwater flow system are investigated. The entire study area is initially conceptualized within a typical karst aquifer framework. Readily available data on climate, groundwater water levels, satellite geology, water chemistry, hydraulic tests, borehole hydrographs, borehole fracture logs, water strikes, geomorphology, supplemented with fracture field mapping and groundwater temperature logging, are used to delineate and study structures, structural controls, hydraulic response and to conceptualize the groundwater flow regime of the Kombat Aquifer. The results indicate that tectonic facies, layering, geomorphology, relief and relative position along the flow system largely influence the distribution of storage, permeability, hydraulic head stability, vertical and horizontal flow patterns, as well as the geometry of the Kombat Aquifer groundwater flow system. A comparison of groundwater temperature of the recharge and the discharge areas shows a temperature increase of about 5oC. An analysis of hydrograph recession curves enabled the understanding of the hydraulic response as well as the hydro_ dynamics of the flow system and confirmed the co-existence of two mutually inclusive groundwater flow components. The statistical examination of transport parameters reveals a very high tendency of dispersion, suggesting that extreme transport values could be more significant to groundwater flow parameterization than average values. A joint combination of blocky fracturing, flat relief and decreasing proximity to discharge zones enhance the long-term safe yield and hydraulic stability of production boreholes. Hence areas that are dominated by parallel fracturing, high elevation and long distances to discharge zones have the most unstable hydraulic head response and the lowest borehole yields. Results from hydraulic tests show that two permeability networks co-exist in different combinations and define the physical framework within which groundwater resides and moves. The connectivity between the two permeability networks characterise the hydraulic response of the Kombat Aquifer to groundwater withdrawal.

Site characterisation aims to obtain fundamental data needed to describe the subsurface flow pathways and distribution of contaminants. The study describes the application of various geohydrological techniques as complimentary tools to characterise an LNAPL contaminated fractured - rock aquifer on the Beaufort West study area in South Africa. Field investigations were designed to define and determine the properties of the fracture preferential flow paths responsible for LNAPL transportation in a typical Karoo fractured â rock aquifer system. The research places emphasis on the integration of results to maximise the subsurface geological understanding in particular location of fracture features chiefly responsible for facilitating LNAPL migration and distribution. The core and percussion drilling explorations, cross - correlated with borehole geophysics, were valuable for geological subsurface investigations in particular locations of bedding fractures, which are often associated with high hydraulic conductive flow zones. Tracer and pump tests were conducted to determine hydraulic and mass transport parameters respectively. Hydraulically conductive bedding plane fracture flow zones were identified by integrating results from the geological core logs, borehole geophysics and aquifer tests. The chemical characterisation of the study area was conducted by means of organic hydrocarbon, inorganic water analyses and volatile organic carbon measurements in the soil during air percussion drilling. Based on the findings, the hydrogeological structure of the formation was conceptualised as a fractured sandstone aquifer, characterised by bedding plane fracture preferential flow paths at contact areas, with shale and mudstone formations. The study findings demonstrate the merit and value in the application of various geohydrological tools to complement one another for optimised site understanding. The findings and recommendations of the case study are not necessarily confined to LNAPL contaminated fractured - rock aquifers, but may also be applicable to other types of contaminants in fractured - rock aquifer formations.

Vaalharts Irrigation Scheme is not only the largest in the country it is known as âThe Food Basketâ. In 1875, Mr Ford, a Government Surveyor got the idea that the Vaalharts area has irrigation scheme possibilities due to the topography of the area. The proposal was approved by government in 1833. Planning, soil tests and more surveys to investigate the possibility were done. A weir was constructed, in the Vaal River, 8.5 km upstream from Warrenton, to deviate water to the Jan Kempdorp/ Hartswater area. In 1938 the first farmers received plots. Today there are almost 1200 plots vary in size from 25 â 75 ha it cover a total area of 35 302 ha. At the start of the irrigation project the water table was 24 mbgl by 1971 it has risen to 1.5 mbgl and waterlogging was experienced. Streutker studied what the cause of the watertable rising were. The feeder canals were ground canals and it leached to the water table causing the rise, the canals were lined. The water table remained high, in 1976 Gombar & Erasmus investigated the possibility to drain the area with boreholes. It was a solution but to expensive, The water in the Spitskop dam in the Harts River, were all the drain water flow to do not show parallel deterioration and accumulation of salt as the groundwater in the irrigated areas. A research done by Haroldt & Bailey investigated where does the salts and water go. Findings was that there are a âsalt sink â present, mainly due to a perched water table and if at some stage the sink will be exhausted it would have severe effects. A 2004 research was done to find the âsalt sinkâ. Boreholes were drilled to study the groundwater characteristics, piezometers were installed, to check the possibility of two aquifers. The study concluded that water levels do not differ more than centimetres in the deep and shallow water systems. Water quality as profiled in piezometers indicated no major stratification of groundwater. The deep lying aquifer does not perform separately, thus no âsalt sinkâ. This study was done to conclude what is the effect of the irrigation on the groundwater and the following was done: ï§ Planning and Installation of piezometer network ï§ EC profiling of the piezometers ï§ Monitor groundwater levels and ECâs ï§ Determine Hydraulic Conductivity ï§ Sample collection and chemical analyses ï§ Monitor flow of drains in the K block ï§ Develop groundwater level contour maps ï§ Develop and run a model to estimate drainage needs ï§ Calculate salt and water balance A Piezometer network consisting of 246 piezometers were installed between Taung in the North and Jan Kempdorp in the south, 208 were surveyed for XYZ coordinates and used for monitoring. The water levels and EC values were measured four times over a period of a year to cover all seasons. The average water level was 1.63 mbgl and the EC average were 191.5 mS/m. Twenty five piezometer sites were selected to cover as much of the soil types present as possible, to determine the hydraulic conductivity. It was between 0.002 and 5.2 m/d. A map was generated to visualize it, and the values were used in the modeling of the drain zones. Water and salt Balance: The leaching requirement to ensure sustainable farming is 611.5 mm/a. According to the water balance it is 562 mm/a. Incoming salts through irrigation water = 4.65 t/ha/a. The TDS determined in 1976 averaged 1005 mg/l, in 2004 it was 1350 mg/l, an average increase of 13 mg/l/a. During the research period it were 1476 mg/l, an increase of 96 mg/l in 5 years an average increase of 19.25 mg/l/a. Irrigation salt not drained = 0.8 t/ha/a Upgrading of all infra structure is essential. Internal subsurface drainage should be cleaned and replaced and the spacing should be decreased to drain the area more effective. Effective drainage would minimize the salt loss prevent a salt build up and have a positive influence on farming and crop quality in the area. The drained water can be reticulated to a transpiration pond to recover the salt thus preventing it from influencing nature and activities downstream.

The project site experienced LNAPL spills in the recent past. In the characterisation of the site it was necessary to investigate the physical properties of the vadose and saturated zones. It was found that temperature, saturation, phase-distribution, the hydraulic properties and water levels contributed to the LNAPL being vaporised. The attributes of the soils substantiated the vaporisation model. The geology was found to be dominated by interbedded sandstones and mudstones, underlain by a dolerite sill. The pollution plume was delineated at the study area and an appropriate management plan was proposed for the site. MNA was shown to be an effective management option.

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This study was aimed at studying bulkflow parameters in groundwater systems at littoral zone of the Modder River. In this thesis, all the aspects were synthesised and exemplified by incorporating a multidisciplinary perspective to develop a sound conceptual framework of the alluvial stream aquifer system. Hydraulic characterisation of the near aquifer system was achieved by acquiring data from a 6-spot pattern well network from which lithological, aquifer hydrogeology, and groundwater hydrogeochemistry characterisations were comprehensively undertaken. The aquifer overburden was estimated to have the permeability of 2.42m/d when its textural classification was found on average to consist of 22% clay+silt and 77% very fine sand. The geology of the study area is typical of the Karoo geology. This was affirmed by massive mudstone bedrock of the Ecca group underlying the study domain. The unconsolidated sediments of gravel, sand and silt, overlie this Karoo mudstone. Therefore, the aquifer is a three units and unconfined alluvial stream aquifer situated in the alluvial deposits along the course of the Modder River. The main units of the system are the upper unit, middle unit and lower aquitard made up of the overbank-fine sand deposits, gravel and mudstone respectively. Groundwater is a bicarbonate type water and falls along a mixing line from sulfatechloride type water to calcium-magnesium type water. This water was found to be both unpolluted sodium enriched and chloride enriched strongly be attributed to forestation of the site where evapotranspiration rates are widespread. Groundwater plots close and parallel to GMWL indicating that recharge is primarily derived from the direct infiltration of precipitation. The δ18O and δD composition of water from the sampled wells indicates that water from all wells drilled in the Riparian or Bank storage aquifer is isotopically lighter than water from wells located on the Terrestrial aquifer. Tritium ranges are indicative of modern water suggesting that the possible influx source might have been precipitation or precipitation derived water. In other words, the groundwater gets recharged with modern rainfalls and has short circulation time in the ground indicative of short travel time. The plot of pH-Tritium indicates that the majority of the samples fall within the rage 6 to 8.5 attributed to recharges with modern and highly neutralised rainfalls. This also suggests short groundwater circulation time in the ground. The groundwater samples with the lowest nitrate concentration were the ones with the lowest tritium level indicating that, although the groundwater source lies on agricultural land, it has not been contaminated by nitrate fertilizers. Groundwater head differences yield the hydraulic gradients from terrestrial aquifer towards riparian aquifer. On average the hydraulic gradient is 0.0083. Flow direction over the entire study domain generally trend SE, sub-perpendicular to the regional surface water flow direction. The EC-profiles show the gravel unit as a major groundwater conduit as shown by a jump in EC values at this unit and this unit is the same water source for all the wells that intercepted the gravel. The transmissivity of the siteâs aquifer ranges between 0.3m2/d and 164m2/d. Highest transmissivity estimated at a maximum level are observed in wells located in the riparian aquifer. The unconfined aquifer specific yield is in the order of 0.005- 0.023. Darcy velocity was estimated at 4.16m/d for CYS1BH4 and natural flow velocity for this well was ultimately estimated at 1.81 m/d. On the other hand, Darcy velocity for CYS1BH3 was estimated at 9.01 m/d with natural flow velocity ultimately estimated at 3.92 m/d. Last in the list is CYS1BH5 whose Darcy velocity was estimated at 11.24 m/d and natural flow velocity ultimately estimated at 22.4 m/d. The estimated velocities are relatively high and this observation holds true for transmissivities so high. Baseflow calculations gave a negative value signifying no base flow contribution of groundwater in to the river. This suggests that most groundwater is used up by the riparian vegetation.