Quantitative characterization of hydraulic conductivities of aquifers is of fundamental importance to the study of groundwater flow and contaminant transport in aquifers. A conditional approach is used to represent the spatial variability of hydraulic conductivity. Briefly, it involves using qualitative and quantitative geologic borehole-log data to generate a three-dimensional (3D) hydraulic conductivity distribution, which is then adjusted through calibration of a 3D groundwater flow model using pumping-test data and historic hydraulic data. The approach consists of several steps. First, classify the lithological information obtained from geologic borehole-logs into representative texture categories; second, establish a quantitative correlation between laboratory measured corescale hydraulic conductivities and texture; third, generate a 3D hydraulic conductivity distribution using a genralized kernel-estimator method; fourth, upscale the core-scale hydraulic conductivity values such that the vertically averaged value at each location matches the field-scale value estimated from pumping tests; and fifth, use hydraulic data to calibrate the 3D field-scale distribution to account for regional-scale characteristics. The approach is applied to a trichloroethene (TCE) contaminated large-scale Superfund site. Based on the good agreement between simula.tions and observations, the results are considered reasonable and realistic. A number of nonideal processes and factors may contribute to the decreasing contaminant removal rate observed at the site. Most of the quantitative analyses of nonideal transport behavior have been conducted using data collected from column or small-scale field experiments. Studies extending such analyses to regional-scale contaminant transport are rare. In this study, a fully 3D transport model is developed to evaluate the effects of various processes/factors on the regional-scale nonideal TCE transport. Based on the analyses, it is found that while large-scale heterogeneity of hydraulic conductivity and ratelimited desorption have significant impacts on TCE transport and cause some nonideal behavior, their impact is not sufficient to account for the extensive tailing exhibited by the observed concentrations in the groundwater entering the treatment plant. Rate-limited dissolution of immiscible liquid appears to be the most likely primary cause of the extensive nonideal transport behavior observed at the site. The impact of the nonlinear sorption and the local-scale heterogeneity on TCE removal appears to be insignificant.

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Research Project Technical Completion Report, Project No. G828-24, Prepared for the U.S. Department of the Interior, September 1984. / / With the growing problem of ground water contamination by volatile organic substances, drinking water sampling programs are being initiated throughout the United States. A need was recognized for a manual on well water sampling that would bridge the gap between highly technical documents and over -simplified reviews. A primer was therefore developed on establishing and implementing a sampling program. Current information was collected by means of both library research and extensive contact with public agency employees and practicing hydrologists. Portions of a sampling program that required explanation included selection of priority wells, proper sampling at the well head, sample preservation and shipment, chain of custody procedures, laboratory selection, quality assurance and data evaluation. Explanation of these steps is intended to help ensure the legal defensibility of any collected data.

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Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Aral, Mustafa; Committee Member: Guan, Jiabao; Committee Member: Kim, Seong Hee; Committee Member: Luo, Jian; Committee Member: Uzer, Turgay.

M.Sc. / In a country such as South Africa, there is a rich diversity of cultural, social, traditional and religious practices. The issue of death takes on a similar diversity, as such responding to death through a burial practice differs to varying degrees with regard to burial containment, burial material and burial procedure. The last few decades have seen an increasing recognition of the impact of human activity on the environment and the critical need to transform our approach on how we plan, lead, manage and monitor our activities. The subject of death has always been sensitive, resulting in the impact of burial remains outside the mainstream environmental critique. A sustainable development approach need to be applied to the issue of burial, and best environmental options should be adopted with sensitivity to social, religious and cultural practices. As the need for land urban development increases, the available space for cemeteries is decreasing. Of the twenty-eight cemeteries in the City of Tshwane Metropolitan Municipality, thirteen are filled up. Therefore, more space is required to bury the dead. It is also recognized that significant increases in the number of deaths due to the HIV/AIDS pandemic is causing problems for already stretched cemetery facilities throughout many parts of South Africa. Research by Fisher (2002) has shown that cemeteries have a fairly severe pollution potential, especially if situated incorrectly. Leachate produced in a cemetery is of a pathogenic nature and can pollute surface and groundwater if located too closely. In black rural areas, most cemeteries were sited by the chiefs and kings of the area, since no legislation existed to govern the cemetery sites. As a result most cemeteries were poorly sited and now possess potential health hazards for our groundwater. Groundwater is a hidden treasure for sustainable development and it plays a vital role in the community, especially in the rural areas. Groundwater is a vital resource in South Africa and sufficient measures should be taken to prevent such additional pollution. This study was undertaken to establish whether poorly sited cemeteries have an impact on groundwater quality, and how can this impact be minimized or eliminated. Therefore, the groundwater quality of Ditengteng village was analyzed chemically and microbiologically. Chemical sampling indicated that the turbidity and the colour of the water do not comply with the South African Bureau of Standards (SABS) for drinking water and the concentration of iron and manganese, which are colouring the water and may cause health hazards if consumed over a long period. Microbiological sampling results indicated that even a once-off consumption of water could cause serious health hazards. The samples collected recorded poor water quality. Despite this fact the community at Ditengteng still use this water for bathing, drinking and cooking. Since piped domestic water supplies are not available, the community depend on that water for survival. This study also indicates that an incorrectly sited cemetery can lead to the contamination of groundwater due to leachate.

M.Tech. Biomedical Technology / Previous studies have reported on the potential health risks associated with direct contact with chemicals (such as DNAPLs) via inhalation or drinking of contaminated groundwater. Dense Non-Aqueous Phase Liquids (DNAPLs) enter into groundwater through incorrect storage or disposal and pose risk to human health. Industrialization contributes considerably to contamination of ground water with waste disposal practices leading to the deposition of hazardous waste at geologically/hydro-geologically unsuitable locations. Many hazardous chemicals found their way into groundwater by this mean and might cause problems if ingested in drinking water. Most of these compounds undergo only limited degradation in the subsurface, and persist for long periods of time while slowly releasing soluble organic constituents that present hazardous health effects (both toxic and non-toxic) to humans.

Gold mining in South Africa resulted in vast volumes of waste material, mainly in the form of tailings material. Poor management of most of the tailings dams resulted in the release of acid mine drainage that in some cases caused soil degradation and water contamination underneath and around these sites. Although many tailings dams have been partially or completely reclaimed, their contaminated footprints pose a serious threat to the water quality of the underlying aquifers (e.g. dolomitic aquifers). This study investigated the geotechnical, mineralogical and geochemical parameters of eleven selected partially or completely reclaimed sites situated near Johannesburg. The main objective of the field and laboratory experiments was to assess the pathway of contaminant migration resulting from acid mine drainage from tailings materials through the unsaturated zone into the groundwater system. Comparing extractable contaminant concentrations with a soil standard from literature represents the environmental short-term impact. In contrast, total element concentrations in the soil compared with background values were used to describe the long-term impact or worst-case scenario. Extraction tests have shown that only a minor portion of contaminants (i.e. Co, Ni and Zn) is mobile in acidic soils. This implies that plant growth could be limited because of phytotoxic elements occurring in the topsoils, complicating rehabilitation measures. In addition, the soils often contain anomalous trace element concentrations, providing a pool for future contamination. Buffer minerals will eventually be depleted and the subsequent acidification of the subsoil, could result in the remobilization of contaminants from the subsoil into the groundwater system in the long term. It is important to understand the parameters, which control the balance between retention and mobility of contaminants in soils. Therefore a risk assessment approach would be required for all tailings dams and reclaimed sites to identify those sites, which need rehabilitation and to define the type and extent of remedial measures. Minimum rehabilitation requirements at reclaimed sites could consist of soil management measures such as liming and the addition of organic material and fertilisers to minimise the contaminant migration from the topsoil into the subsoil and groundwater as well as to provide suitable conditions for vegetation growth and future land use. Removal of remaining tailings and excavation of those portions of the soil, which are excessively contaminated, are necessary. Tailings dams which pose a high risk to the environment would require a well-engineered soil and vegetation cover to limit rainfall infiltration into the impoundment, and thus to reduce the oxidation of sulphide-bearing minerals such as pyrite. Long-term monitoring is an absolute prerequisite to ensure the success of rehabilitation, and therefore the safe use of land and water. / Thesis (PhD)--University of Pretoria, 2007. / Geology / Unrestricted

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science in hydrogeology, School of Geosciences. Johannesburg, 23 May 2016. / Groundwater treatment by chemical precipitation is a popular form of remediation at mines that are in operation. The water quality status at the implementation of the PAT in this study was compared to the water quality status after a six-month period of active remediation. Chromium is very important as an industrial metal owing to its numerous uses in a variety of industries. The objective of the remedial action is to intercept the Cr(VI) plume, abstract contaminated groundwater and chemically treat it on the surface. The long-term (15-year) objective is to eventually reduce Cr(VI) concentrations in the aquifer(s) to below 0.05 mg/ℓ. The PAT system was implemented as a mediumterm (5-year) strategy to intercept the Cr(VI) contamination plume during migration to prevent it from negatively impacting on groundwater users downstream of the mine. In the vicinity of the three PAT systems’ abstracting wells, water levels declined by an average of 2 m compared to the same period in 2014. Periodical fluctuations in the fractured aquifer are reflective of the influence of fractures on groundwater flow. In the aquifer, hydrochemical signatures show evidence of mixing between the primary and secondary aquifers. The treatment system has been successful in reducing Cr(VI) to Cr(III) and precipitating Cr(OH)3. The treatment system was designed to treat Cr(VI), other elevated constituents and generally high dissolved ions are not treated in this remedial process. Sulphate concentrations increase after treatment as a result of the addition of Fe(II)SO4 for chromate contamination treatment purposes. The simulated reaction path shows that the transformation of CrO4 2- to Cr2O3 in the treatment system is not immediate. The Cr(VI) to Cr(III) transformation is irreversible, this is beneficial as the water is abstracted from more reducing conditions, and the treatment ponds are open to the atmosphere thus the conditions following dosing with Fe(II)SO4 are oxic and chromate complexes are stable over a wider range of Eh-pH conditions than Cr(III) compounds. This ensures that the efficiency of the dosing system is not reversed in Settling Pond B. The modelled flow paths are similar to the inferred flow vectors in the plume capture zone. Fracture flow is the dominant type of flow, the fault zones and dykes create high permeability conduits to flow. Flow paths are parallel to fault lines or the lateral dimension of dykes; flow occurs along fractures and deformation zones. The reduction of Cr(VI) concentrations in some of the peripheral sampling points indicates that the PAT system has been successful in capturing the chromate contaminated water through pumping. Keywords: Hexavalent chromium, groundwater pollution, remediation, pump-and-treat, fractured aquifers / GR2016