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By K Barns, H Law, T Whebell, P Scobie, T Perkins, J Siliezar, M Larson

With processing a variety of orebodies at Glencore’s Ernest Henry Mining (EHM) has come a changing mineralogy and more complex requirements for treatment in the concentrator. From mid-2013 and into 2014 the grind size required to achieve sufficient mineral liberation for production of a quality concentrate has reduced significantly. What was once a final P80 of 35–45 microns was forced to 20 microns. This has necessitated some creative changes to the flow sheet that previously had a 937?kW Vertimill regrinding a rougher concentrate to 40 microns. EHM is able to utilise an existing M10 000 3 MW IsaMill previously used for magnetite processing, to provide a quick convenient solution without large scale capital expenditures. Operating the Vertimill and IsaMill in parallel in closed circuit was successful at reducing the P80 of the regrind circuit to below 20 microns which increased the final concentrate grade by four per cent. This circuit and intermediate circuits used are discussed. Performance of the Vertimill and IsaMill is compared for efficiency optimisation to improve the overall circuit performance.CITATION:Siliezar, J, Whebell, T, Perkins, T, Law, H, Scobie, P, Larson, M and Barns, K, 2014. From magnetite to chalcopyrite – a story of versatility and efficiency at Glencore’s Ernest Henry mining?operation, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 85–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Ishikawa K, Kikuchi T, Tokairin Y

Roadheader, developed from coal cutting machines, is generally classified as a tunnel excavation machine for soft rocks in respect to excavation mechanism, machine structure, weight, engine output and so on. In recent tunnel works, however, there is an increasing demand for changing from blasting to mechanical excavation by roadheaders to avoid environmental problems such as noise and vibration. But there exist various difficulties in excavation of harder rocks by roadheaders. In order to explore the possibilities of roadheader excavation, we performed field and laboratory experiments. In the field experiment, roadheader model S-125 (Mitui Miike Machinery Co.,Ltd.) was tested for various rocks of wide range of hardness, and excavation capacity and wear of picks were measured. In the laboratory test, cutting performance of the picks was tested by our cutter testing machine. This report describes thr: of these experiments and discussions :n possibility of applying boom-type tunnelling machines to hard rock excavation based on these experimental data.

Jan 1, 1987

By G Gibson

Realising that current roadway development performance levels were unlikely to sustain new generation high-capacity (15 Mt/a) longwall mines then being planned, the Australian Coal Association Research Program (ACARP) established a Roadway Development Task Group (RDTG) in 2005 to develop a research strategy targeted at improving roadway development performance in Australian longwall mines. The initial phase of the project identified a number of factors that differentiated best practice mines from others, and proposed a multi-faceted research strategy encompassing both short- and long-term research initiatives, including:conducting regular benchmarking studies across the industry to identify factors contributing to improved performance and to monitor performance trends,conducting regular industry roadway development operatorsÆ workshops to facilitate the transfer of successful roadway development improvement initiatives throughout the industry and facilitate networking between development practitioners,development of alternative skin reinforcement and containment measures that would eliminate the use of steel mesh and enable face support systems to be fully automated,development of automated bolting and mesh handling systems that would enable operators to be removed from the immediate face area,development of a body of knowledge of industry roadway development practice,development of a web-based information management system to capture and transfer emerging developments in roadway development practice and technology,reviewing the Australian civil tunnelling and underground metalliferous mining sectors to identify practices and technologies that could potentially be utilised to improve roadway development performance, anddeveloping a new generation high-capacity mining system capable of +10 metres per operating hour for 20 or more hours per day (CM2010). The paper reports on the progress of the above initiatives and outlines strategies to continue the pursuit for improved roadway development performance.

Jan 1, 2008

Thank you and good morning. I am delighted to be here and to see so many of my colleagues and competitors. The general topic of this week's conference - World's Best Practice in Mining and Processing - suggests a focus on mining and processing. I am somewhat of a `jack of all trades and a master of none'. But I'm not even a jack when it comes to mining and processing technology and practices, and so I will leave those topics to speakers better 'qualified than I. Instead, what I would like to do is give you my thoughts on the best management practices of mining. You see, the times are changing for the mining business. There is great uncertainty in our industry. Anyone who received their education in an English-speaking school probably remembers the famous poem `Invictus' by William Ernest Henley. The two most famous lines from that poem are, if you remember, `I am the master of my fate; I am the captain of my soul'. The fact of the matter is that the metals industry, including the copper industry, is not the master of its fate. To a great extent we're at the mercy of forces over which we have little control, such as the world economy or political situations in individual countries. The copper industry is like a surfer at Manly - we can't influence where the wave is going; all we can do is stay in front of the curl and on our board. Historically, discovering, developing and processing ore reserves were the primary facets of our capital intensive business. To stay competitive today, we must invest equally in intellectual capital - our employees - in order to succeed in the face of economic, regulatory and political challenges and global competition (Schonberger, 1986). Everyone seems to have a different theory about being competitive. A lot of people use sports analogies when talking about competition. Others, like American businessman and former US presidential wanna-be Ross Perot, take a more interesting approach. In Mr Perot's hypothetical corporation, competition is a lot like having a snake in a factory. If someone sees a snake, the first thing they do is create a committee on snakes. Then, the committee on snakes meets and discusses the problem for a couple of years. The most likely course of action is nothing. Everyone figures that the snake hasn't bitten anyone yet, so they just let him crawl around the factory floor. Perhaps a vice president of serpentine affairs is appointed to continue watching the snake - making sure it doesn't grow. Ross Perot sees it a little differently. In his corporate world, business needs to build an environment where the first guy who sees the snake kills it. Of course in our industry, we better make sure the snake isn't on an Endangered Species List before we go after it! I am not going to talk about competition and competitive forces in terms of sports or snakes, but I would like to share some thoughts with you about how the mining industry can better utilise competitive thinking to get ahead and stay there. You may be wondering how an executive from a 160-year-old company could know much about competitive spirit, but the founding ancestors of Phelps Dodge were wizards at identifying

Jan 1, 1995

When a thin film of volatile matter is deposited under vacuum on a polished coal surface, and the coated surface is examined microscopically in plane-polarized reflected light, colour changes are observed which are characteristic of the various macerals present. The colour changes appear to be mainly due to interference between light reflected at the upper surface of the film and at the film!coal interface. A variety of source materials for the volatile matter required have been tested, including powdered bituminous coal, coal tars, boron oxide, and certain resins. Bituminous coal gave the best results.

Jan 1, 1970

Solid Energy New Zealand Limited (æSolid EnergyÆ) is a state-owned coal mining company, producing 4.0 Mtpa from a number of opencast and underground mines in the Huntly, West Coast and Southland regions in New Zealand. The company currently exports 2.1 Mtpa of coking coal. Exports are expected to grow strongly over the next five year as the company expands production into new semi-soft and thermal coal reserves. Domestic coal demand is also expected to grow strongly, particularly in the North Island, as the Maui gas field reserves diminish, and thermal coal becomes more important for electricity generation and meeting the energy needs of forest processing and other industries. Solid Energy is expanding and developing its risk management practices across all areas of the business: strategic planning û extensive use of scenario analysis and probabilistic modelling over a 20 year period; investment decisions û development and application of a rigorous six stage æProject Assessment GuidelineÆ process for all new mine developments; geological and geotechnical risk assessment techniques û use of best practice techniques including seismic surveys; financial risk management û a dynamic approach to hedging based on effects based analysis of Cash Flow at Risk analysis against preset risk tolerances; risk financing û the use of a captive insurance subsidiary, and the experiences of a small coal company seeking to obtain insurance cover on a æhardÆ international insurance market; and integrated risk management û the challenges of trying to implement a broad integrated risk management approach across the company, that supports implementation of strategic objectives as well as meeting æcompliance or legislative basedÆ risk management requirements.

Jan 1, 2003

By Clifford C. E

1 eat my peas with honey I've done it all my lifeIt makes them taste rather funny But it keeps them on the knife.Innovation is that elusive characteristic which involves the determination of multiple and unique response to a problem, and then commitment to and action from the best of the alternatives.

Jan 1, 1993

The geographical region of South East Asia is variously defined, but generally agreed to include the Asean group - Philippines, Malaysia, Thailand, Singapore and Indonesia. Other regional countries, such as Vietnam, Laos, Burma, Kampuchea etc. are of course geographically part of the region, however in economic terms, they play a minor role. It is the Asean group that dominates present economic activity and provides the overwhelming opportunity for commercial development. My experience in South East Asia has been gleaned over 15 years of regular travel in the region. More recently, we have established company offices in Malaysia, Singapore and Indonesia to extend and deepen contacts with major customers. This progressive development is an integral part of a planned growth pattern and will be discussed in more detail shortly. South East Asia is a rapidly developing economic growth centre, a fact which is clearly recognised and accepted by most commentators. An important question is then to be asked: Why has the region been relatively neglected by Australian, U.S. and European industrial supply companies? I will attempt to address this question in the context of industrial minerals and propose some ideas as to how effective sales programs could be developed. Firstly, let's consider the market potential provided by countries within the region. It is reasonable to suggest that industrial growth in S.E. Asia over the past 20 years has been generally steady and in some cases, explosive. Until recently, this growth has predominantly been driven by development of internal (regional) demand. Population growth and rising living standards have ensured that basic industries have enjoyed a solid uptrend in sales and production. The industries which most benefitted from regional economic development over this period were, interestingly, those which we understand to be major users of industrial minerals - glass, ceramics, paper, surface coatings, cement, refractories, rubber and plastics. Each of these industrial sectors has been influenced by different growth stimulii over a 20 year period. Nevertheless, they also enjoy a common feature which ensured an above average performance. All sectors are fundamental to an environment enjoying rising living standards and rapid growth in general prosperity. More recently, internal growth factors have been overtaken by a recognition that manufactured products from the region are competitive in export markets. This comparatively recent development provides the most interesting possibilities for higher value industrial mineral raw materials. Let me explain: For 20 years, industrial growth in South Asia has essentially been focused on satisfying domestic demand. Finished quality of manufactured items was orientated to a developing market more interested in cost than aesthetics or long life. This was reflected in raw material specifications, which often did not exist and at the best were undemanding.

Jan 1, 1989

In blasting large tonnages of ore or material, the economy of the operation 'depends mainly on the mine manager's judgment in placing the holes to the best possible advantage and in determining the most effective size of hole to suit the conditions and requirements.The placing of holes is often looked upon as a problem involving so many uncertain factors that the application of simple mathematics is impossible. The uncertain factors arise when dealing with strata of different character, in hardness toughness and resistance to shearing.A study of the practice at many mines where all types of strata from hard ore to relatively soft overburden, and even coal, is being mined, suggests that the problem is not as complex as generally believed. There is, without doubt, some uniformity in the amount of burden given to holes of equivalent dimensions, regardless of the material being mined. The reason is simple. With too great a burden hard rock will not break out and soft rock will "bull". The nature of the strata is taken care of by the strength, quantity and distribution of the explosive charge and, to some extent, the spacing of the holes.It is because burdens are uniform in all classes of strata met with in mining, that a formula can be used to design blast hole layouts.The formula introduced in this paper is empirical as it is based on prevailing practice. It has been tested and proved remarkably accurate against every example available to the writer. Many thousands of blast holes, at many different mines, are represented by the examples given in the attached tables; to give further examples would only mean, unnecessary repetition. At the Mount Morgan Mine...

Jan 1, 1952

The corrosion of aluminosilicate refractories by soda from three different sources has been studied by microscopic methods. Sodium sulphate from oil ash, sodium chloride used in glazing structural clay products, and sodium borate from borax-impregnated wood ash have fundamentally the same effect on the refractories. The soda is the chief medium of reaction and fluxing, the sulphur, chlorine, and boron being volatized as sulphuric, hydrochloric, and boric acids.INTRODUCTIONBecause of their strong fluxing action, alkalis are one of the main causes of corrosion and slagging of refractories.The action of potash and soda on refractories follows somewhat similar lines, although it is common for one alkali to be greatly in excess of the other. The course of the reaction in a number of cases of alkali attack has been studied by microscopic and chemical methods. For example, the action of potash on blast furnace refractories was studied by Kraner (1942) and Rigby and Richardson (1947), who described the occurrence of various potassium aluminium silicates. Its action on cement kiln refractories was described by Brisbane, Segnit, and Weymouth (1957). The action of soda on glass tank refractories has been studied by many people, for example Bisby (1956) and Resch (1954). Clews, Hugill, and Green (1940) made a microscopic examination of the attack by soda on silica bricks from a gas retort.Some recent cases of corrosion of aluminosilicate refractories which were brought to the attention of the Division of Building Research, C.S.I.R.O., illustrate phenomena which occur under conditions different from those...

Jan 1, 1964

Flow Sheet Simulation of Municipal Waste Treatment Processes

Sep 13, 2010

Test Work on High Throughput Diamond Tracer Recovery from Alluvial Recovery Tailings with a Containerised Optical Sorter Under Real Production Conditions Worldwide alluvial diamond deposits are traditionally processed with dense media separation and XRF sorters, hand picking or grease tables. The test work conducted verifies the performance of an optical sorter detecting the transparency of particles for diamond recovery from the DMS concentrate, eg XRF-sorter and handpicking tailings. The containerised setup enables economically feasible, high throughput, semi-mobile setups to retreat recovery tailings from alluvial and also primary deposits. The test work has been conducted with quartz and glass particles, which are less transparent or comparably transparent, under realistic production conditions on a 600 mm belt machine with an installed electrical power of only 21 kW. The results show that 99 per cent recovery can be reached at a throughput of 10 t/h in the -8 + 2 mm fraction and at 22 t/h in the -25 + 8 mm fraction. At a throughput of 18 t/h a recovery of 88 per cent has been assessed. At a further escalation of the throughput, dust in the sorter container made sorting impossible in the coarse fraction and the recovery decreased significantly in the fine fraction. Analysis of the belt coverage indicates that higher throughputs of the coarse fraction can be fed onto the optical sorter if the dust extraction system is improved. The results are basis for the decision to conservatively feed 20 t/h of the coarse fraction and 17 t/h of the fine fraction in day to day production. The settings have been applied to sort alluvial recovery tailings in South Africa and will be applied to sort the recovery tailings of a primary deposit in Lesotho. The test work has shown that an optical sorter can be used to retreat recovery tailings with high throughputs. The compact setup of a screen and a 9 m standard container enables semi-mobile, temporary setups for small recovery tailings dumps and remote areas. In addition, sorting on transparency ensures the recovery of high value low-fluorescent diamonds.

Sep 13, 2010

A Process for the Flotation of Chrysocolla

Sep 13, 2010

By R C. Schodde

The future of any mining company depends on maintaining and growing its access to high-quality mineral resources. Often the true size of a given resource is not fully recognised until after mining has commenced. Also, the strong desire to increase production puts pressure to expand the resource base of the mine to get maximum value out of the capital employed. This, plus diminishing M&A opportunities and declining world-class greenfield discovery rates, makes brownfields exploration a high priority activity in any operating company. For the success and long-term survival of the company it is critical that this is done well. The primary aim of brownfields exploration is to find or acquire new deposits within economic transport distance of an existing mine that will add materially to shareholder value through: mine or capacity expansion, displacement of lower-margin ore from the mine plan, preserving and extending the mine life, and ensuring potential value is understood in order to maximise potential future mine development or exit. A number of strategic principles are important in any program designed to achieve these aims: understanding the life of mine (LOM) production profile and the related key drivers for exploration, understanding the dynamic nature of the brownfields search space, understanding and measuring depletion of the brownfields search space, understanding the potential of the near-mine region, investing in exploration technology to expand the search space, and investing in a basic geological understanding of the ore-environment. Examination of the LOM profile will highlight critical issues facing development plans for the mine including future grade and throughput issues, key technology requirements or innovations and scenarios for increased production. Exploration targets in the brownfields program should address these key issues. Often it is as æsimpleÆ as keeping mine development sufficiently far ahead of extraction to allow time for the various phases of exploration and resource assessment drilling. Because of the low additional capital costs required, expansion of the brownfields search space is strongly leveraged to: metal prices, development of new markets, incremental operating cost reductions, strategic changes in downstream requirements in integrated businesses, depletion of higher unit-value ores, and new technologies (both extraction and exploration). Therefore the brownfields search space is likely to incrementally expand through time and must be regularly reviewed. This is also important as any given search space will be progressively exhausted, resulting in smaller and higher cost discoveries. It is therefore important to monitor and critically review sustained trends of increasing brownfields discovery cost. The first wave of discoveries in any camp are usually empirically driven and do not need a strong geological understanding. However, an improved geological understanding is critical to making the next generation of hidden discoveries. To illustrate these points, a case study was carried out on the exploration and development history of the Kambalda nickel camp. Over a period of 40 years, more than 40 deposits were found containing over 1.7 million tonnes of nickel metal. Efficient mines need to maintain reserves for operating flexibility. Consequently, the company needs to clearly understand the global resource in order to maximise its full potential. In addition, understanding the full brownfields potential earlier in the development of a deposit rather than later, creates optionality through the flexibility that this understanding brings to future development choices. To ensure best practice in attaining this aim, the roles and responsibilities of the exploration team and the mine operation should be clearly understood. It is important for the explorers and the operators to have shared views about what needs to be done. Typically, mine operators would be accountable for identifying future resource requirements to support the life-of-mine production schedule whilst explorers would be accountable to ensure best-practice assessment of brownfields exploration opportunities. This would include an assessment of the global undiscovered endowment in the regional near-mine area. The balance between brownfield exploration drilling and resources to reserve conversion will need to be decided to ensure efficient operations are maintained. Both need to agree the optimum level of brownfields funding taking into account: urgency to replace or grow reserves, and quality of opportunities (relative to those elsewhere). The ultimate cost of ignoring the full brownfields potential of an operating asset can be significant, ranging from inefficient and poorly planned operations, lost opportunity cost and resultant value through under-utilised resources and, in the worst case, early exit from the asset at the bottom of the commodity cycle û leaving behind huge amounts of shareholder value.

Jan 1, 2006

By M Brockman, M Cowan, A Robeson

"Sunrise Dam Gold Mine (SDGM) is located 820 km from Perth, 220 km from Kalgoorlie—Boulder and 55 km south of Laverton in Western Australia. The SDGM main pit had successfully operated since 1997 and was due to be completed during 2012. An opportunity existed to extract the high-grade crown pillar – 600 kt @ 7 g/t for 135 koz by either open pit or underground methods.The crown pillar was the 60 m (vertically) thick remaining part of the high-grade Cosmo orebody between the top of the paste filled underground mine stopes and the planned base of the final open pit shell.There were two major difficulties being considered when choosing the underground or open pit options:a major wall failure in the upper section of the main pit wall directly above the crown pillar restricting access from the base of the open pit to the top of the crown pillarimpact of a high rainfall event while the crown pillar was being mined from either surface or underground resulting in flooding of the underground mine workings.This paper will discuss the following issues:the process to identify and evaluate the risks in both options using knowledge based modelling software; this technique allowed the evaluation of a complex set of assumptions to arrive at the preferred optionremediation of the Watu failurethe selection of the preferred option and the challenges encountered before, during and after the extraction of the crown pillarthe planning and geotechnical work to ensure the safe extraction of the crown pillarsuccessful outcomes transitioning from open pit operation to a solely underground operation.Citation:Robeson, A, Cowan, M and Brockman, M, 2016. A Case Study on the Assessment, Planning and Extraction of the Crown Pillar at Sunrise Dam Gold Mine, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 115–136 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

An Integrated Solid Waste Management Method for Western Macedonia, Greece

Sep 13, 2010

By M Brady

"It has long been recognised that the barometer infl uences areas of underground coal mines that havebeen sealed off from the current, or active, mine workings but it appears litt le formal research hasbeen done on how the barometer aff ects the goafstream sample point. Based on statistical analysis of samples from a number of mines from Queensland and New South Wales it can be concluded that there is a direct correlation between the barometer and oxygen concentration at a goafstream sample point. To help mitigate some of the high consequence hazards within the underground coal industry and protect the health and safety of the persons within that environment, many monitoring tools are utilised. A control recognised in management plans prescribed under New South Wales and Queensland legislation is the need to conduct monitoring to identify the early warning signs of spontaneous combustion. One of the monitoring tools utilised involves a bagsample being collected from a goafstream sample point then returned to the surface for analysis.When the sample is incorrectly collected, the resultant analysis from a gas chromatograph provides litt le value to the persons charged with the obligation of operating the coal mine at an acceptable level of risk. This, therefore, increases the probability of spontaneous combustion leading to a loss of equipment, mine and in the worst case, life. When the sample is collected correctly, the analysis presents early warning signs of low level oxidation allowing corrective action to be taken, to prevent the oxidation accelerating to spontaneous combustion. The eff ect the barometer has on this sample point should be recognised and the knowledge imparted to persons who conduct sampling to remove a variable in the bag sample collection process. This will ensure the persons operating the mine have a bett er understanding of what is happening within their longwall goaf."

Jun 1, 2012

By D M. Hunter, S M. Iveson, K P. Galvin

For low density materials such as coal, density-based fractionation of particles via the sink-float method is relatively simple due to the availability of liquids of suitable density; however, for high density minerals, suitable heavy liquids are less available and those that are available are expensive and pose significant hazards. At best, sink-float separation can be performed up to densities of 4400 kg/m3 with the use of Clerici’s solution at elevated temperatures. Hence the direct measurement of grade-recovery and density-partition curves is problematic. Therefore, in most cases, beneficiation plants must rely on methods such as QEMSCAN, density tracer particles or very limited information to guide them in the design and optimisation of their plants.This paper describes a density-fractionation method utilising laminar flow through a system of parallel inclined channels to generate a series of overflow fractions at different flow velocities. Here the particles are subject to precise hydrodynamic forces with minimal dispersion or mixing. The size distribution of each overflow fraction at a given flow velocity is obtained using a laser particle size analyser, and combined with a laminar flow model to deduce the corresponding density distribution. The paper describes the application of the method to measure the separation achieved using a REFLUX Classifier to obtain the corresponding feed, product and reject ‘washability curves’, and in turn the full partition surface. Approaches used to corroborate the findings are discussed.CITATION:Hunter, D M, Iveson, S M and Galvin, K P, 2017. A batch elutriation technique for the density-based fractionation of iron ore, in Proceedings Iron Ore 2017, pp 195–104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

After a snap-shot survey of water quality of streams draining various coal measures carried out in 2000 - 2001, West Coast Regional Council expanded its monitoring programme to better establish the condition of streams draining coal mining areas and to characterise the variability of water quality with respect to stream flow. Samples were collected for water quality indicators such as pH, sulphate, turbidity, conductivity, temperature and dissolved oxygen as well as macro-invertebrates, fish and assessments of stream habitat. Water quality sampling was carried out at 27 sites on 21 streams located from Page Stream near Seddonville in the north, to Seven Mile Creek near Dunollie in the South, and to Garvey Creek east of Reefton. There was relatively low variability of pH, conductivity and sulphate concentrations at most of the sites sampled. Conductivity and sulphate concentrations reduced with increasing flow and pH generally increased. Significant effects on macro-invertebrate and fish populations were identified at several of the sites where water quality sampling was undertaken. Of the water quality parameters tested, macro-invertebrates were mostly affected by pH. Although not sampled directly (conductivity was used as a surrogate) heavy metal concentration may explain some of the variation in macro-invertebrate communities. Three creeks affected by mine drainage were sampled for fish and no fish were present. Fish appear to be more sensitive to acid rock drainage that invertebrates. Using data from this survey and other studies conducted in the region, the total length of stream that is actually or highly likely to be adversely affected by acid rock drainage was estimated at 125 km. This figure is useful as a gauge as to the magnitude of the issue in this region and for setting of priorities for remediation. However, as it is only an estimate based on limited sampling sites, it should be used with caution.

Jan 1, 2003

A key driver to the success of a tunnelling project (the project) is the management of hydrogeological risk. The hydrogeological risk, if not managed, may cause significant impacts on the overall performance of the project. Impacts may include groundwater quality impairment due to contaminant transport and acid drainage from disturbed geology to groundwater, and groundwater lowering. The groundwater lowering and quality impairment may cause tunnel failure, with consequences such as injury to humans, as well as reduced property and environmental values, potentially costing millions of dollars to sponsors of the project. Depending on the nature of the contaminants and level of hydraulic connection of bedrock fracture along the length of tunnel, the contaminant transport may reduce structural strength of the tunnel due to corrosive action of contaminants such as acid drainage. The groundwater lowering can lead to varying degrees of ground settlement, posing threat of tunnel collapse. The management of hydrogeological risk includes:detection of potential pathways for contaminants into and around the tunnel,identification of factors responsible for the lowering of groundwater, and development of strategic measures to control groundwater lowering and contaminant transport. The paper presents an in-house hydrogeological risk management model named Vedanta-THRM (tunnel hydrogeological risk management). The model uses Risk Management Standard AS/NZS 4360:2004 (Standards Australia, 2004), Pressure State Response framework developed by Organisation of Economic Cooperation and Development, and Interaction Matrices. The Vedanta-THRM identifies important characteristics, processes and events of potential hydrogeological risk and develops control measures for managing hydrogeological risk throughout the life cycle of the project. The Vedanta-THRM was applied for a project in the early stages of planning and found to be useful in assessing, evaluating and reducing the hydrogeological risk in a managed approach that potentially increased the performance of the project. The application results also provided management options for use by project sponsors and insurance industry, which included tunnel risk financing options and options for equity investors to choose among various returns under different tunnel credit ratings.

Jan 1, 2008