The vital role of water within the mining industry, both as an asset which generates value as well as a shared natural resource requiring responsible stewardship, have long been recognised. Due to extreme climate changes, an increasing population density and poor water management, securing of water has become a global challenge and water scarcity will continue to be one of the greatest challenges facing mine water management. There is no simple recipe for mine water management and regulations by environmental authorities, along with past polluting practices, are forcing mining operations to improve and prioritise their water consumption. Accordingly, this sector is expected to be increasingly required to demonstrate leadership through innovative water use management. A mine water balance is considered to be one of the most important and fundamental tools available for mining operations as management begins with a basic understanding of where water is sourced from, and where it is utilised. With this kept in mind, a mine water balance should be based on a holistic systems model approach with an appropriate relationship between the required level of complexity in the model structure and purpose. Excessive detail can cause the model to become clumsy and tend not to focus on strategic water management principles. Emphasis should be put on a system approach, taking into consideration the main interactions, feedbacks and functional relationships between the various parts of the whole system. An overall mine water balance that superimposes different water systems can be divided into a process water system and a natural water system. The natural water system is associated with the intrinsic hydrological cycle and is often disregarded due to uncertainties. It can however significantly impact on mine water usage and losses as indicated in this case study. Consequently, decision making and management options should be based on the evaluation of the system as a whole and inclusion of the natural system as a component of the mine water balance is imperative for accurate quantification. The natural system includes a surface water environmental circuit as well as a groundwater environmental circuit. Surface and groundwater resources have historically been managed separately, but more than ever before, interaction between these two systems are required to facilitate effective resource management. Mining activities have a major effect on the modification of the hydrological regime and the influence of increased hydraulic conductivity along with mining induced recharge, should be evaluated as part of the adapted mine water balance. Furthermore, mine dewatering predictions and climatic scenarios must be incorporated to reflect site conditions more accurately. As poor water management poses an operational risk to mining operations, this sector has developed novel ways to respond to water issues in differing circumstances and has illustrated the ability to turn risk into opportunity. Now, more than ever, special measures are needed to identify options for life-of-mine strategies and initiatives for water conservation and management. Future focus should be to continue investigation and implementation of the water use strategies in order to improve performance across operations and encourage engagement with other water users. Moreover, to share experiences, learn from others and contribute to water discussions and debate at local, national and international levels.

The study describes the effect of calculating a generalised mean transmissivity or hydraulic conductivity value for a region or aquifer system as it pertains to South Africa. Resource determination of an area is usually driven by the determination of the bulk flow parameters, such as hydraulic conductivity and storativity values. At this stage a decision is usually made on the basis of either maintaining the area under natural conditions (no pumping), or an abstraction (pumping) scenario is envisaged. In both instances water levels, hydraulic testing and distribution of the water resources (aquifer) are required. Since it is not possible to evaluate the total area for these parameters certain assumptions have to be made such as that an average bulk flow parameter for an area can be determined. In wide-ranging situations a simple average of observation points is assumed to be sufficient. A systematic research approach was followed in which a three-step process was used to evaluate methods of calculating these mean values. In the first instance a conceptual model approach was used, and all bulk flow parameters were generated by means of matrices to represent the natural system. Three typically employed mean values (arithmetic, geometric and harmonic) were calculated for two different dimensional matrices, i.e., N x N (N = 100 and 1000) with different hydraulic conductivity zones. In addition the relative difference between these hydraulic conductivity zones were steadily increased to mimic observed parameters in the field, i.e. typical hydraulic conductivity of shale (K = 0.01 m/d) versus a fracture zone (K = 100 m/d). In all instances the harmonic mean performed the best and as the number of sample sets were increased, a reduction in mean values were observed. As part of the conceptual model approach, two typically encountered scenarios were investigated, i.e. natural flow and forced gradient conditions. Under these two scenario conditions the harmonic mean performed the best to estimate the actual observed hydraulic conductivity value. Secondly, case studies were presented which highlighted the influence of sample size on observed parameters. Additionally, the effect of the differences between the low and high hydraulic conductivity zones on the calculated mean value as a function of sample size, was also reported. In all of these case studies the harmonic mean was the closest in approximating the observed hydraulic conductivity. It is evident from this section that the number of host rock (formation) hydraulic conductivity values plays a critical part in the mean value calculation since it is general practice in South Africa not to report low yielding borehole hydraulic test values. In the third step, the results were discussed in the context of a more general approach to the problem of calculating a regional mean hydraulic conductivity of transmissivity value. The estimation of representa-tive transmissivity values were discussed as seen from a stochastic modelling perspective as well as from the deterministic point of view. A comparison between main stream groundwater and oil industry specialists were noted in which both groups share the fundamental training but differ on the methodology of determining the observed transmissivity values. The impact of horizontal heterogeneities and different fracture networks was discussed and the influence these features have on the actual transmissivity value obtained, i.e. the influence of internal boundaries on hydraulic test data. Scale effects were also addressed from a regional perspective, with a focus on apparent scaling and the actual regional transmissivity value which should be obtained. The findings of this study are that in essence using geostatistical methods are not advised if regional transmissivity values are required from a South African perspective. The reason behind this statement is that the distribution of transmissivity values in an area does not follow the basic precepts that are required for these methods to work. In general the values are discontinuous in distribution and statistically skewed. Furthermore, the presence of transmissivity areas or points that differ significantly in magnitude, i.e. transmissivity values which differ by more than two orders, can be located within one meter from each other. The explanation of this phenomenon is the presence of dolerite dykes, which create baked-fractured zones with exceptionally large transmissivity values compared to the extremely low transmissivity ranges of the surrounding country rock (shales, mudstone and siltstone). In addition, the lack of data concerning low-yielding or âdryâ boreholes is a major source of concern since it influences the calculated mean value to a high degree.

Acid Rock Drainage (ARD) is expected to take place as soon as rock or coal that consists of sulphide minerals is exposed to the surface and comes into contact with oxygen and water. Water not only acts as catalyst, but also as a transportation medium of the yellow boy precipitates which in turn deteriorates the condition of the environment as well as water resources. Due to the long-term irreversible impact that ARD has, minimisation of this condition is an important factor to be looked at by mining companies. Worst cases have been reported by the Department of Water Affairs in and around coal and gold mines in the Witwatersrand and Witbank areas. This has brought about a necessity to explore pre-mining investigations into different lithologies to be aware of possible changes that might occur in the environment once mining commences. An evaluation of ARD was also done on the coal and rock samples to have better knowledge of what will be released in the environment and water resources as more mines are introduced in the Waterberg Coalfield.. Controlling ARD means to control the acid generating reactions of which mineralogy stands at the core of the whole reaction process. Coal deposits in South Africa largely consist of shales; mudstones, siltstones and sandstones which contain clay minerals, quartz, carbonates and sulphides. Problems that are associated with ARD (results) include decreased pH values and increased values of metals, acidity, sulphate and dissolved and suspended solids. The sulphate concentration is caused by sulphide minerals that are in the mining environment and undergo oxidation, thus bringing out the presence of sulphate. The investigation took place in four areas, namely Resgen, Grootegeluk (Exxaro), Sasol and Sekoko. A total of 214 samples were selected from the borehole core to conduct an Acid Base Accounting (ABA) (from the interburden, overburden and coal samples), 29 samples were selected for whole rock and mineralogical analysis, and 8 selected for kinetic tests. Results from the ABA and the kinetic tests leachate were further analysed for major and trace elements using the ICP-OES (Inductively Coupled Plasma- Optical Emission Spectrometer). ABA results show that the interburden and coal samples have a higher risk of producing acid upon oxidation when comparing it to overburden samples. They have a higher concentration of neutralising minerals that can neutralise the acid produced through sulphide minerals as oxidation takes place. In the Sasol samples, which were collected from the full succession that includes the Volksrust and the Vryheid formation, the closed Net Neutralising Potential (NNP) varied from -306.19 to 121.05 kg/tonne CaCO3. The results indicate that there is higher potential of acid production than neutralisation. Grootegeluk samples taken from the overburden showed a closed NNP that varied between -0.33 to 310.80 kg/tonne CaCO3 which classifies the samples as having more potential of neutralisation than acidification; the same case applies for Resgen with closed NNP that is between -68.96 and 57.74 kg/tonne CaCO3. Sekoko consists of the lowest number of samples that have a low risk of acid generation with more samples having a sulphide âS that is more than 0.3%. Mineralogical analysis indicates that there is a presence of pyrite, calcite and dolomite present in accessory to minor concentration. Minerals quartz and kaolinite are found in all the samples constituted in major to dominant concentrations. Results from the whole rock analysis which correlate with mineralogical analysis were SiO2 and Al2O3 which have the highest weight percentage and is similar to the presence of quartz and kaolinite. The average Fe2O3 that is 6.73 wt.% for Sasol and 3.28 wt.% for Resgen, is higher than the average CaO and MgO which is the result of the calcite and dolomite mineral. Leachate analysis from the ABA shows that metals become more soluble as acidity increases. An increase was noted in metals such as iron, magnesium and cadmium, which is a greater threat than the acidity that results from the drainage. Further tests were carried out after the completion of the ABA analysis; kinetic tests were performed on samples that gave inconclusive NNP results. The analysis showed the long-term behaviour of different samples with the EC and pH changing over time. Samples with a lower pH continue to produce more sulphate, while calcium continues to increase until it is depleted from the samples. The Waterberg Coalfield has not yet experienced major environmental deteriorations due to ARD; this is likely to change as more mines will be added to the area.

The engineering properties of a South African class F fly ash were studied as a potential base liner for a dry coal ash dump. In order to increase the unconfined compression strength, lime and gypsum were added to the fly ash while also aiding in reducing the hydraulic conductivity. Lime was added in the range of 1 to 10% while the gypsum amounts were varied at 1% and 3% per specimen. The constant head method was used to determine the hydraulic conductivity of compacted specimens in the laboratory. Gypsum was observed to have more influence in reducing the hydraulic conductivity as specimens with 3% gypsum had a more reduced hydraulic conductivity that those with 1%. The variations in lime percentages did not appear to reduce the hydraulic conductivity but rather displayed higher values than fly ash specimens without additives when higher percentages of lime were used. A fly ash admixture of 3% lime and 3% gypsum was found to have the lowest hydraulic conductivity of 2.27 x10-9 m/s after 60 days of percolating with brine water. The unconfined compression strength also appeared to be more influenced by gypsum than lime percentages as specimens with 3% gypsum obtained higher strength values than those with 1% gypsum added. Unreacted lime was observed in specimens with higher percentages of lime added and these specimens also presented lower strength values. The addition of lime and gypsum was observed to have limited the release of some trace elements from fly ash. The secondary mineral ettringite was detected and could have possibly precipitated and captured out these toxic elements. An attempt was also made to increase the plasticity index of fly ash using lignosulphonate and values recommended by the South African legislative guidelines for liner materials were obtained. The plasticity was however not retained with subsequent leaching. Two multi-layer liner systems were loaded under different compaction rates in permeameter cells with fitted inflow and outflow points. The primary liners of both systems were able to contain over 95% of leachate that percolated through a waste layer. Compaction rate was found to affect the liners performance as primary liners with a higher compaction rate had less seepage than primary liner compacted at a lower rate. An addition of lime and gypsum improved the overall engineering properties of fly ash to levels accepted by the South African legislative guidelines for a liner material that is able to line hazardous waste. Even though concentrations of some trace elements in fly ash were reduced by addition of lime and gypsum the level of some of these trace elements remain above the threshold set by South African legislative guidelines and therefore remains a health and environmental concern.

This thesis aims to fiimish an understanding of the water fluxes and storages occurring at the subcatchment scale in Goss Moor, a large lowland wetland in Cornwall, UK. Goss Moor constitutes approximately 5 km^ of poor fen and similar wetland areas sited on clayey alluvial and periglacial deposits in the base of a broad/shallow headwater valley. The bedrock is kaolinised granite and pelite. The hydrological characterisation was achieved using variables measured directly on site, using spectrally derived stream flow components and using flows output from a caUbrated numerical model of transient groundwater flow beneath the wetland. The study demonstrated the use of distributed spectral filtering for source area characterisation and of numerical modelling for investigathig the role of groundwater flow in the wetland. Certain stream flows into and out of the wetland were monitored at an hourly resolution. At each site, slowly- and quickly-varying components of flow were discriminated using a digital filter whose response was based upon an observed summer recession. Quick flows thus defined were found to be conserved during translation from the upsfream inputs to the outflow, although in-channel dispersion eliminated their flashiness. Conversely, the slow flow component was found to vary more rapidly at the wetland outflow than at the main stream entry, indicating the dominance of a different source of flow upon exit from the wetland. Overall stream flow gained by 50% in traversing the wetland site. Evapotranspiration (ET) rates in the wefland and in the outer catchment were estimated using the Penman-Monteith formula with measurements near or within the site. The calculations indicated that evapotranspirative losses would be greater from the wefland than from the remainder of its catchment due to the presence of surface water. U.S.G.S. MODFLOW was used to model the groundwater flow in the alluvium beneath the wefland. Shallow groundwater levels at 20 piezometer sites within the wefland, together with information on stratigraphy, rainfall and ET, provided boundary and caUbration data for the model. The results of in situ slug tests were used to define the aquifer permeability for the model in the transient calibration. Storativity and ET were adjusted to produce a match with the observed summer water table decline. A reduction of ET with falling water table greatly improved the match, and it was postulated that the declining water table had therefore dropped below the zone of greatest evapotranspirative uptake. By combining the various sources of data, the wefland's water budget was estimated. The numerical modeUing showed that groundwater flow to the river accounted for between only 0% and 3% of the total output from the wefland surface and substrata. ET accounted for 20% and surface runoff for 77-80%. Although wefland surface flow was not measured, the water budget showed that a substantial summer reduction in stored water would result if no peripheral inflows were received onto the wetiand surface. In the annual water budget, such peripheral inflows were of a magnitude similar to that of the rainfall input to the wefland. Together, these two inputs traversed the wefland surface to provide the increase in slow flow in the river on its exit from the wetiand. The implications of the water budget for the management of the wetland are briefly discussed.

No description available.

No description available.

Anaerobic ammonium-oxidizing (anammox) bacteria perform an important step in the global nitrogen cycle: oxidizing ammonium and reducing nitrite to form dinitrogen gas in the absence of oxygen. Anammox bacteria from the Planctomycetes phylum have been identified in a variety of natural environments but their role in groundwater ammonium oxidation has been unclear. Recent isotope studies have suggested that anammox bacteria are likely active in ammonium attenuation at contaminated groundwater sites; however, only limited biomarker-based data confirmed their presence prior to this study. I used complimentary molecular and isotope-based methods to assess the communities of anammox performing organisms at three ammonium contaminated groundwater sites in Canada: quantitative real-time PCR (qPCR), denaturing gradient gel electrophoresis (DGGE), DNA sequencing of 16S rRNA genes (with both Sanger and Illumina technologies), and ¹⁵N-tracer incubations. DNA sequencing and qPCR results demonstrated that anammox performing organisms were present at all three contaminated sites, and that they were among the dominant bacterial community members for at least one particular site (Zorra, Ontario). In addition, anammox bacterial diversity was variable. One site possessed four of five known genera of anammox performing organisms although the dominant anammox bacteria at all sites belonged to the Candidatus Brocadia genus. Isotope data from two groundwater sites showed that denitrification and anammox occurred jointly and although denitrification was the dominant process, anammox was responsible for maxima of 18 and 36% of N₂ production at these sites. By combining molecular and isotopic results I have demonstrated the diversity, abundance and activity of these anaerobic chemolithoautotrophic bacteria; these results provide strong evidence for their important biogeochemical role in attenuating groundwater ammonium contamination.

No description available.

Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 87-92). / xi, 92 leaves, bound ill., col. maps 29 cm