The evaluation of risk is often performed assuming static conditions when in reality, conditions are continually evolving. In the following dissertation, the evaluation of risk with changing conditions over time is considered for a specific project - placing overburden into an active, open pit mine. The research focuses on the geotechnical components of risk with the goal of identifying whether and to what extent it is possible to place overburden on mined out portions of the open pit slopes. The relevant factors, which change with time or impact risk, are first identified and an evaluation is performed to estimate a probability of failure at various stages of the project life. Potential damages are then assessed by first evaluating the run out distance and post failure geometry of a slope failure and then estimating the percentage of material that would have to be removed to continue extraction of ore. To convert the uncertainty into economic terms, unit values for savings that result from placing overburden in the pit and costs associated with cleaning up failure debris are estimated. The probability of failure, potential for cleanup, and unit values are combined to produce estimates of the likely costs and benefits associated with dumping overburden in the open pit.The results of the analysis indicated that risk varies considerably with time. However, it is possible to place overburden in the central portion of the open pit up to a limit of approximately 80 million tons while maintaining a positive net value of expected costs and benefits.

The subject of this study was the effect of surrounding vegetation on the species composition of the dumps after black coal mining. The species data from dumps and their surroundings up to 100m were recorded during the vegetation seasons 2009-2011 and consequently analysed using ordination methods (DCA and CCA) and univariate statistics. The data on land cover and percent of the old forests (present in the surroundings in years 1836 -1852 up to 100m and 1km from the margins of the dumps) appeared to have significant effect on the present species composition of vegetation on the dumps.

High extraction mining techniques have produced the need to mitigate and understand ground movements associated with this technology.  Tools such as the Surface Deformation Prediction System (SDPS) facilitate sound scientific decision making in the industry and has continually improved since its inception in 1987.  The capabilities of SDPS have expanded on an as-needed basis.  Currently, the regulatory climate has emphasized the need to understand the impact of underground mining on surface waters, physically and chemically. The SDPS program is used to conduct an analysis of ground movements to assess optimal barrier pillar size for stream protection.  Typical analytical and empirical methods used in mine planning were compared against SDPS methods to ensure the validity and advantage to the use of SDPS for this purpose. Finally, underground mining effects on stream chemistry and health were explored by studying the heavily mined and industrialized watershed of Dumps Creek located in Russell County, Virginia.  This watershed has been identified as being impaired since the Virginia 303(d) List of Impaired Waters was created in 1994.  Currently, there are two pumps staged in the headwaters region of Dumps Creek that help to maintain water levels in an inactive underground mine.  The pumping is necessary to control methane levels that rising water could force into an active underground mine that lies stratigraphically above the inactive mine.  Water is pumped on an as-needed basis and discharges directly into Dumps Creek.  Historic measurements of stream conductivity and benthic health scores were compared to assess whether a correlation exists between the two measurements.  These measurements were compared based on regulatory decisions that emphasized that conductivity is a direct indicator of stream health in all watersheds. Scientific contributions associated with this research include: Further developments in the use of SDPS programming in order to account for stream protection on a case by case basis for both mine panel and surface water protection by optimizing barrier pillar size in relation to a nearby stream; the analysis of available and currently obtained water chemistry data in a mining impacted watershed in attempt to further research to appropriately characterize and mitigate specific problems in order to improve stream health; and, assessment of the complexity of water chemistry impacts from underground mining as related to stream health indicators in different chemically dominated watersheds. / Master of Science

Faculty of Engineering School of Civil and Enviromental Engineering 9506023j PMISTRY@WEBMAIL.co.za / This report investigates the viability of satellite remote sensing in monitoring the rehabilitation of coal discard dumps. Four levels of thermal monitoring data were assessed in this project. These were: ground and below surface temperature probes; aerial thermal and atmospheric monitoring surveys; high altitude aircraft; and satellites. Remote sensing methods measure only variation of temperatures on the surface of the dump. Fires on discard dumps are sub-surface fires, and the depth and extent of the fire below the surface cannot be easily inferred. The resolution of satellite sensors is a limiting factor for detecting individual hotspots on dumps. Small mine dumps occupy just a few pixels and the position of fires cannot be accurately assessed. Although the larger dumps are discernable, the variation of temperatures across the dump cannot be easily determined. For the present, aircraft monitoring may be the most viable means of monitoring spontaneous combustion in coal discard dumps, until satellite resolutions improve further.

>Magister Scientiae - MSc / The Physics Department at the University of the Western Cape and the Environmental Physics group at iThemba labs have been conducting radiometric studies on both land and water. In this study a 7.5 cm X 7.5 cm NaI (Tl) detector was used to study activity concentrations of primordial radionuclides in soil and sand samples. The detector and the sample were placed inside a lead castle to reduce background in the laboratory from the surroundings such as the wall and the floor. The samples were placed inside a 1 L Marinelli beaker which surrounds the detector for better relative efficiency as almost the whole sample is exposed to the detector. Additional lead bricks were placed below the detector to further reduce the background by 20%. The NaI detector is known to be prone to spectral drift caused by temperature differences inside and around the detector. The spectral drift was investigated by using a ¹³⁷Cs source to monitor the movements in the 662 keV peak. The maximum centroid shift was about 4 keV (for a period of 24 hours) which is enough to cause disturbances in spectral fitting. There was no correlation between the centroid shift and small room temperature fluctuations of 1.56 ºC. A Full Spectrum Analysis (FSA) method was used to extract the activity concentrations of ²³⁸U, ²³²Th and ⁴⁰K from the measured data. The FSA method is different from the usual Windows Analysis (WA) as it uses the whole spectrum instead of only putting a ‘window’ around the region of interest to measure the counts around a certain energy peak. The FSA method uses standard spectra corresponding to the radionuclides being investigated, and is expected to have an advantage when low-activity samples are measured. The standard spectra are multiplied by the activity concentrations and then added to fit the measured spectrum. Accurate concentrations are then extracted using a chi-squared (χ²) minimization procedure. Eight samples were measured in the laboratory using the NaI detector and analyzed using the FSA method. The samples were measured for about 24 hours for good statistics. Microsoft Excel and MATLAB were used to calculate the activity concentrations. The ²³⁸U activity concentration values varied from 14 ± 1 Bq/kg (iThemba soil, HS6) to 256 ± 10 Bq/kg (Kloof sample). The ²³²Th activity concentration values varied from 7 ± 1 Bq/kg (Anstip beach sand) to 53 ± 3 Bq/kg (Rawsonville soil #B31). The ⁴⁰K activity concentration values varied from 60 ± 20 Bq/kg (iThemba soil, HS6) to 190 ± 20 Bq/kg (Kloof sample). The χ² values also varied from sample to sample with the lowest being 12 (Anstip beach sand) and the highest (for samples without contamination of anthropogenic nuclei) being 357 (Rawsonville soil #B28). A high χ² value usually represents incomplete gain drift corrections, improper set of fitting functions, proper inclusion of coincidence summing or the presence of anthropogenic (man made) radionuclei in the source [Hen03]. Activity concentrations of ⁴⁰K, ²³²Th and ²³⁸U were measured at four stationary points on the Kloof mine dump. The fifth stationary point was located on the Southdeep mine dump. These measurements were analysed using the FSA method and fitting by "eye" the standard spectra to the measured spectra using Microsoft Excel. These values were then compared to values obtained using an automated minimization procedure in MATLAB. There was a good correlation between these results except for ²³²Th which had higher concentrations when MATLAB was used, where 16 Bq/kg was the average value in Excel and 24 Bq/kg was the average value in MATLAB.

Fire presents a significant risk of the formation of toxic combustion gases. These substances further endanger fire squad units and nearby residents. Toxic gases are responsible for almost 50% of all fire casualties and cause one third of fatal casualties. The amount and composition of gases depend to a great extent on the conditions of thermal degradation especially temperature and the amount of oxygen in the surrounding atmosphere. Prevention or minimisation of consequences of formation of toxic gases involves a rapid and a quality analysis. For this purpose, the methods that proved to be the best suited are gas chromatography and mass spectrometry combined with micro-extraction to solid phase. This work involves analysis of combustion products of selected materials and study of their toxic characteristics. These are especially wood, oil products, various types of rubber and plastic materials. Using analysis of these combustion gases more than 300 hundred substances have been identified. These are especially carbon oxides, nitrogen oxides, sulphur oxides, volatile organic substances, polycyclic aromatic hydrocarbons, etc. Monitoring of combustion gases was performed even in the vicinity of large fires. The findings were complemented by information from expert studies and events of past years. In case of identified substances which present the greatest health risk, the most significant toxic characteristics were described with emphasis on acute exposition, symptoms of intoxication and possible consequences. Following all these facts protection measures are suggested in relation to the formation of toxic combustion gases.

Species composition of soil algal and cyanobacterial communities was investigated in thirteen sites of different toxicity of spoil material on dumps in the Sokolov mining area (Czech Republic). The adaptation ability of various algal and cyanobacterial species to live in toxic environment and the effect of different amendments (wooden coal, organic matter, dolomitic limestone) of toxic soils were tested both in laboratory and field experiments. According to results, species composition corresponded to environmental characteristic (pH, conductivity, substrate type). Some green unicellular algae grew successfully in extracts from the most toxic substrate and seemed to be well adapted to low pH conditions. Results indicate that increase of pH is a basic precondition for the establishment of more diverse and abundant algal flora in highly acidic sites.

The engineering properties of waste spoil from phosphate mines in Southeastern Idaho were determined through field and laboratory testing. The testing included compaction tests, grain size analysis, powder x-ray defraction tests, permeability tests, compression tests, triaxial and direct shear strength tests, and nutrient analyses. Based on these tests, the slope stability and settlement characteristics of phosphate spoil dumps were investigated. The study showed that the foundation is an important component of the stability of a spoil dump. Hypothetical examples were used to illustrate possible modes of foundation failures. Such failures might occur when weak foundation soils exist or when there is a lack of embankment-foundation preparation prior to the disposal of waste material. When considering failures through only the middle waste shale embankment material, the study showed that dumps constructed by end-dumping the spoil material over angle of repose embankments or by scraper filling the material in horizontal lifts will be adequately safe against slope failure if: o Embankment slopes are graded to 21/2 horizontal to 1 vertical or flatter. o Proper precautions are taken to prevent the build-up of a phreatic surface near the top of the embankment. The study also showed that post construction settlement in spoil dumps can be attributed to: o A slow continuing settlement which is linear with the log of time. o Saturation collapse settlement which occurs with increases in the moisture contents. Post construction settlement in spoil dumps is caused principally by increases in the moisture content in layers of middle waste shales and soft cherts. A rationale method for predicting magnitudes of post construction settlement in spoil dumps was also developed as part of this study.

For successful restoration of unstable ecosystems in the dumps recreating a fully functioning lan dis needed. Dump substrates often have poor grain composition, extreme pH or are toxic. They also lack important recent organic matter, which improves the overall quality of the soil and is therefore necessary for the development of quality and fertile soil. Therefore, restoration of ecosystems in the dumps is initially very slow. A number of reclamation measures was invented to accelerate this process - for example, heaping up of topsoil to dump substrates. With organic matter present in the topsoil soil formation is faster and often with their physical and chemical properties differ significantly from then developed soils. There has already been number of works written considering development of soils on the Velká podkrušnohorská výsypka so far, none of which, however, did not affect grasslands. The aim of this work was to obtain complete information about the development of chemical and microbial properties of soils that were recultivted by reclaimed topsoil and grassed and then to compare them with developments in the areas of overgrown spontaneous succession. It was found that the total carbon content increases with time only in the reclaimed areas and maximum of the increase is in the depth of...

Surface mining and its associated territory disturbance is generally perceived negatively by society. However, these newly transformed regions may be very important areas of conservation from biodiversity point of view of and emergence of refugia. This thesis investigates the dynamics of the coal dumps and the land cover changes in relation to the occurrence of endangered species of Tawny pipit (Anthus campestris) in the North Bohemia. This area is the only breeding region in the country for this species. The aim of this thesis is to describe land cover change on three coal dumps (Tušimice, Bílina a Vršany) within horizon of four years (2014, 2015, 2016 and 2017). Moreover, another aim was to asses habitat preferences of Tawny pipit based on ornithological findings for particular year. As it is seen from the results, the most significant change occurred at those areas, which were without vegetation cover in the beggining of monitoring and were cover with vegetation later. The category of herbal vegetation was the one which increased the most, as it was caused by spontaneous succession. It showed up that Tawny pipit's most preferred areas are land cover categories coal dumps surface without vegetation, coal dumps surface with herbal vegetation and category buildings, build-up area and transport...