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The Ruttan Cu-Zn mine produced approximately 30 million tons of fine-grained tailings over 30 years. Since the closure of the mine in 2002, the tailings have been systematically dewatered through trenches which drain into Ruttan Lake and into the open pit and underground mine workings. This study evaluated the evolution of the tailings of Cell 3, which was underwater in 2002, and Cell 2, which was already dry and oxidized. Dewatering the submerged tailings in Cell 3 resulted in measureable changes in acidification in pore and shallow groundwater from rapid oxidation of very fine grained sulphides. Depth profiles of the concentration of metals in dissolved and solid fractions, when compared to other studies, suggest that the tailings in Cell 2 and Cell 3 are in an early stage of oxidation and that these tailings will produce low pH, metal laden water for years.

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The ground water regimes of three small, undisturbed (natural) and accessible hard rock catchments representing the South, Midlands and the North of Great Britain have been hydrogeologically investigated and compared. There is a dearth of hydro geological information on hard rock areas in Britain. This is because the general availability of surface water and extensive sedimentary aquifers has not encouraged ground water prospecting in hard rock areas. In view of this, low flow study was considered essential since geology exerts a great influence on its characteristics. This was carried out using baseflow recession analysis. From a combination of practical, empirical and theoretical considerations aided by statistical analysis on a computer, baseflow recession constants which dynamically reflect the physiographic and geologic controls within a catchment were derived for the catchments investigated. These were used to characterise the behaviour of the low flows. A new method which is free of random selection of data for baseflow recession analysis is presented and a model for the curve fitting both by computer and manual methods are fully discussed and its application is also presented. Water balance computations for each of the three catchments is presented in chapter 2. Lithological units were identified by a detailed geological study. These were further investigated using resistivity and electromagnetic methods of geophysical survey. Hydrogeological properties of the aquifers were investigated by pumping test analysis and subsequent comparison of hydraulic conductivities from soils and baseflow studies. A water chemistry investigation of spring, river and rain waters has been carried out to try and defme flow paths of the ground water and this is presented in chapter 7. From these investigations, this research concludes that large community water supplies through boreholes can be economical only in one of the catchments (East Dart catchment). In the other two catchments (Blackbrook and Calder catchments), small community and household supplies are possible through boreholes (in some areas) and large diameter wells.

Determining sustainable water resource utilization rates is an important problem faced by regulatory agencies all around the world. One of the key parameters in determining accurate water budgeting schemes is the rate of water resource replenishment, or ‘recharge’ in groundwater systems. Fundamental questions regarding groundwater recharge include: What is the source of recharge? What is the spatial distribution of recharge? What is the annual average recharge rate, from potentially disparate sources in disparate areas? Answers to these questions can be gained through combining physical and chemical hydrogeological research tools, including stable isotopic compositions. Land-use intensification, including significant increases in dairying, has placed a priority on developing water resource management practices throughout New Zealand. Here we present the first compilation of delta oxygen-18 and delta hydrogen-2 values from individual precipitation events, local surface waters, depression springs, and groundwaters from the greater-Christchurch area. A variety of analytical methods were used in an effort to evaluate the potential use of stable isotopic compositions as tracers of surface-groundwater interaction in the local hydrologic cycle. The results of this thesis found the isotopic variability of Christchurch precipitation to be highly varied. Back-trajectory analysis of single precipitation events exhibit pathways arriving from three principal sources: the Southern Pacific Ocean, the Tasman Sea, and the Tropical Pacific Ocean. Separately, delta oxygen-18 and delta hydrogen-2 values values from these sources show three distinct local meteoric water lines, which are determined to be largely affected by the environmental conditions present in these areas at the time water vapour formation. Intra-storm variation of extra-tropical cyclones support these findings as significant changes in deuterium excess as moisture sources change with southward movement of the low pressure system. Three line-conditioned tests were subsequently developed to compare the relationship between monthly surface rainfall, surface water, and groundwater samples to the respective moisture origins. Surface rainfall, rainfall infiltration, surface waters, and groundwaters all exhibit the least amount of deviation from the Southern Pacific Ocean local meteoric water line. These observations suggest the principle moisture source to Christchurch to be from west-south westerly flow from the mid-latitudes. However, these similarities do not make partitioning their relative contributions to the groundwater system easy. Previous physical and isotopic investigations have shown the dominant sources of recharge to the Christchurch Groundwater System (CGS) are alpine rivers and local precipitation of which there is statistically significant difference with respect to delta oxygen-18 values. A binary single-isotope mixing model allows for quantification of the relative contributions of alpine river and precipitation derived inputs to local depression springs. The isotopic model indicates that approximately 80% of spring discharge was derived from alpine rivers, in good agreement with recently published physical mass balance model results. Deep groundwater flow paths however show groundwater to flow from the Central Canterbury Plains to the CGS. Potentially including losses from the upper Waimakariri River reaches. If included, this places a net recharge amount to the CGS water budget, which if using losses from only the lower Waimakariri River, there is a net loss. Losses from the upper reaches and subsequent groundwater flow into the CGS are likely as there have been no observed declines in groundwater levels even though there is currently a net loss by only using recharge components within the CGS. Ultimately, recharge from groundwater movement from the Central Canterbury Plains may play significant role; however, a much more sophisticated geochemical model is needed to test these theories and determine contributions. This research demonstrates the utility of stable isotopes as tracers of hydrogeological processes, particularly in shallow groundwater, and their potential contributions to the water resource allocation decision making process.

The Ruttan Cu-Zn mine produced approximately 30 million tons of fine-grained tailings over 30 years. Since the closure of the mine in 2002, the tailings have been systematically dewatered through trenches which drain into Ruttan Lake and into the open pit and underground mine workings. This study evaluated the evolution of the tailings of Cell 3, which was underwater in 2002, and Cell 2, which was already dry and oxidized. Dewatering the submerged tailings in Cell 3 resulted in measureable changes in acidification in pore and shallow groundwater from rapid oxidation of very fine grained sulphides. Depth profiles of the concentration of metals in dissolved and solid fractions, when compared to other studies, suggest that the tailings in Cell 2 and Cell 3 are in an early stage of oxidation and that these tailings will produce low pH, metal laden water for years.

Thesis (Ph. D. - Geosciences)--University of Arizona. / Includes bibliographical references.

Thesis (M.S.)--University of Arizona, 1991. / One map on 1 folded sheet in pocket. Includes bibliographical references (p. 146-149).

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1990. / Includes bibliographical references (leaves 209-212).

Thesis (M.S. - Hydrology and Water Resources) - University of Arizona. / Includes bibliographical references (leaves 93-102).