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By C Hoffmann

Given that each year, 30–40 per cent of mining industry deaths are attributable to failures of vehicle interaction controls (EMESRT, 2023), the mining industry is now armed with a growing body of knowledge from EMESRT (Earth Moving Equipment Safety Round Table) and ICMM (International Council on Mining and Metals) global vehicle interaction initiatives over the past years, that enables mining companies, OEM’s and technology providers to work together to develop and implement more effective controls and drive the adoption of capable solutions. Leveraging 20 years of experience as a global technology provider of Proximity Detection System (PDS) and Collision Avoidance System (CAS) solutions for surface mining operations, Wabtec Digital Mine Technology shares key insights for ensuring the effective selection, implementation and integration of these technologies into existing mine site controls and mining operations for effectively reducing vehicle interaction risk enabling mines to drive towards ‘zero-harm’ objectives. Topics covered include: alignment with industry best practice for controlling vehicle interaction risk by EMESRT and ICMM, importance of the maturity of EMESRT levels 1–7 vehicle interaction (VI) control framework, managing expectations that PDS/CAS is a ‘silver bullet’, alignment with industry functional – performance – technical requirements, proximity detection versus collision avoidance, sensor performance and fusion and limitations, rules engine intelligence critical to mitigating nuisance alarms during normal operations, system health monitoring and reporting, human factors engineering and operator acceptance, implementation strategy, installation standards and quality control, change management program, training programs, reporting and data analytics with actionable insights and maintenance strategies. Insights will also be provided on the challenges moving from EMESRT levels 7 (operator awareness) and 8 (advisory controls) to level 9 (intervention controls) as it’s a journey not an out-of-box solution, the growing demand for coexistence of CAS and Autonomous Haulage Solutions (AHS), functional safety approach, value added systems integration and the applicability of new emerging technologies.

Apr 16, 2024

By A G. Dempster, N Barnett, J Oh, S Saydam

NASA’s Artemis III mission is expected to return astronauts to the surface to explore and sample the lunar volatiles by 2026. These volatiles are anticipated to provide scientific insights as to how the Moon was created and economic value to off-Earth operations. These same volatiles can pose health implications to astronauts and Earth based personnel handling lunar regolith samples. Using Australian, USA and NASA airborne contaminant exposure limits and the Lunar CRater Observation and Sensing Satellite (LCROSS) measurements of lunar volatiles in the Cabeus crater ejecta, the minimum mass of lunar regolith that can be safely handled by humans on Earth and in spacecraft can be calculated. This analysis determined a 0.15 grams pure sample of Cabeus crater regolith within a cubic metre of air has enough volatiles to exceed safe working conditions, and 14.9 grams of pure Cabeus crater regolith per cubic metre of air can impact human life. The intent of this analysis is to assist safe handling and exposure calculations for the safe handling procedures of lunar regolith containing volatiles.

Sep 1, 2024

Australia had an active uranium mining industry in the 1950s with uranium oxide being supplied under contract to the atomic energy authorities of the U.K. and U.S.A. In the 1960s, when these con- tracts concluded, domestic production ceased, apart from Rum Jungle, whose production until 1971 was stockpiled. By the 1970s, the demand for uranium from the electrical utility industry had risen sharply and the effects on Australia were notable. The Mary Kath- leen mine re-opened in 1976 but, more significantly, exploration activity suddenly expanded with the re- sult that several world-standard deposits were locat- ed. Western world requirements for uranium based on increasing energy consumption and a changing energy mix, will warrant the development of Aust- ralia's resources. By 1985 our mines could be pro- ducing 9,500 tonnes of uranium oxide yearly and by 1995 the export value from uranium could reach that from wool. In terms of benefit to the community the economic rewards are considerable but, in terms of providing energy to the world, Australia's uranium is vital.

Jan 1, 1978

By J Heyes, R Getty, M Sanapala

Closure is an inevitable part of the life cycle of every mine. Successful closure outcomes critically depend upon early and ongoing integration of closure planning and mine planning. Early and holistic integration minimises residual risk and maximises opportunity to leave a cost-effective, positive legacy for the company, investors and future land users. Both disciplines are inherently interconnected and aim to maximise ‘value’ via trade-offs. Historically, integration of closure into mine plans has been poorly implemented across the industry. There is still a perception that closure planning only starts as the end of a mine life approaches. This inevitably leads to tension when making business decisions, with progressive closure often being deferred due to short-term drivers and incentives. To create a positive legacy after production has ceased, this tension can be managed by transparently and fully informing business decision-makers, such that the impacts of short-term decisions on long-term closure objectives are understood. BHP recently updated a business-wide standard ‘Our Requirements for Closure and Legacy Management’ designed to strengthen collaboration, education and integration of closure across the entire life cycle of the asset. Concurrently, the ‘Life of Asset’ definition was refined to include the postproduction phase, until closure objectives have been met. This paper discusses the criticality of mine planning integration with closure and how updates to Our Requirements sharpen the focus from transactional to transformational planning. These concepts are applicable to any mining operation aiming to achieve successful closure across the full asset life cycle, from exploration to post-production.

Sep 18, 2023

By S Novak

A world-class example of sustainable development in practice, the Local Resource Development Initiative (LRDI) grew from agreements between the Ambatovy nickel mine developers and the Government of Madagascar. A program of training and community development, the LRDI aims to maximise local benefits by optimising the integration of local resources during the construction period of the mine. By local resources, we mean the local labour force as well as local goods and services. Begun in 2007, the foundation of the LRDI is to integrate local resources into the mining project and where gaps are identified, design and implement training, mentoring and other programs to fill those gaps. The principal accomplishments are: the establishment of training centres that trained over 4000 people in little over one year, 96 per cent of whom hired to work at the mine; a support program for local micro, small and medium enterprises that has led to the award of 65 contracts for goods and services with training and mentoring of over 100 local businesses; and a number of special projects that have, among other results, strengthened local agricultural development and created employment for young people. The LRDI provides unique insights into key indicators and lessons learned to strengthen the social and economic sustainability of mining projects in developing countries. The paper will discuss these in terms, among others, of: the importance to project success of upstream planning to address socio-economic issues; the role of civil society and other local partners to strengthen and expand sustainability outcomes, and to spur governments to demand that major projects promote economic and social sustainability; and the integration of mine sustainability with sustained regional social and economic development.

Jan 1, 2009

By D Walker, A Tsvetkov, P Voigt, O Kloiber-Deane

The GPM Gold Operation has been employing an Albion Process™ plant at its Sotk (Zod) gold mine in Armenia since 2014. Long term data from the operation is now being published for the first time. The data presented includes concentrate throughput, as feed to the Albion Process™ plant (tonnes per day), sulphur grade in concentrate (% S), total sulphide sulphur oxidation in the Albion Process™ plant (% SOx) and gold recovery from Albion Process™ plant residues (%). The data provides a basis for evaluation of the effectiveness of the commissioning, ramp up and operation of the Albion Process™ plant. Notwithstanding the impact of a slower concentrator commissioning than expected, the plant demonstrates Series 1 behaviour on McNulty ramp up curves, indicating successful commissioning and fast ramp up. Interrogation of the data and operational experience indicates that this successful operation is a result of a process that is flexible, robust and stable, one that was designed well based on solid testwork results and pilot plant trials during the study phase undertaken by Glencore Technology and Core Resources, and where the local operators were provided with appropriate training in operation of the plant. CITATION:Voigt, P, Walker, D, Kloiber-Deane, O and Tsvetkov, A, 2018. Ramp-up and long-term performance of the Albion Process™ plant at GeoProMining Gold Armenia, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 339–350 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By S Lehane, S Pearce

The characterisation and assessment of waste rock has been the subject of considerable research, and many guidance documents have been published both internationally and within Australia. While these documents provide detailed information on how to characterise waste rock, there is not a great amount of detail on how to determine the optimal waste management options from an operational viewpoint. For example, typical questions that a mine operator would seek answers to include: What placement method should be used (eg end tipping versus paddock dumping)? What is an optimal tip head height for waste placement in a storage facility? How should sulfide grade control be carried out?Defining the contributing factors to waste management and waste material placement and assessing the contribution of each variable directs these assessments towards a semi-qualitative and quantitative methodology. Quantitative methodologies show an increase in the confidence of these assessments by providing logical, measureable assessments.As part of a strategic assessment for waste management at an active mine site, a detailed risk-based investigation of the influence of variables common to waste placement was completed. These variables included placement method, placement height, sulfur grade and material conditioning (eg compaction) on the associated risks of waste material storage. The assessed risks include temperature assessments (potential for thermal take-off as a result of spontaneous combustion), toxic gas production and flow and acid production potential. Applying a numerical modelling approach to the assessment of the different waste material placement strategies allows for the variation in risk to be graphically presented and communicated through risk matrices and histograms.CITATION:Pearce, S and Lehane, S, 2015. Quantitative risk assessment tools to assist with waste management and placement guidelines, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 353–364 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By T Nassis, P Louw, M R. Fry, T du Toit

Business intelligence (BI) and business analytics (BA) are established IT technologies that are used extensively in the business environment. This paper discusses the use of these technologies in production environments and beneficiation plants.Assmang’s Khumani mine is an iron ore operation located in the Northern Cape, South Africa. Assmang Limited is jointly owned by African Rainbow Minerals Limited and Assore Limited. This paper presents a case study of a BI solution applied to this plant, which is used by metallurgists, supervisors and all levels of operations and management to extract and analyse data to control and optimise the operation of the plant.The main advantage of adopting an established BI solution is the ease with which production personnel can extract and analyse data. The data is easily presented in familiar spreadsheets and no IT staff or specific training is required to achieve this.The solution adopted at Khumani mine uses a data mart with a multidimensional model (called an online analytical processing (OLAP) cube) acting as the main repository and source of data. The OLAP cube simplifies the access and analysis of plant data.The OLAP cube stores data in a specifically-designed way, which allows extraction and analysis to be performed quickly. It is designed to hold large amounts of data on a long-term basis, which could be for the life of the plant. It also performs automatic aggregations over many dimensions on a background process.A major benefit in adopting such a BI solution is that it allows common BA methods to be applied. This is due to both the efficient long-term storage of data and the availability of standard BA tools. BA tools are now able to perform data mining, predictive analytics, forecasting and other machine-learning algorithms. This paper presents the possible use of such advanced data analysis methods in a beneficiation plant.CITATION:Fry, M R, Nassis, T, Louw, P and du Toit, T, 2015. The use of common business intelligence and analytics tools in the operation and optimisation of iron ore process plants, in Proceedings Iron Ore 2015, pp 129–138 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By R Hughes

"Spring Creek Mine uses high pressure water to extract the thick Main seam in the Upper Rewanuicoal measures. The extraction method results in the creation of large voids which collapsespontaneously. This can result in the displacement of large volumes of methane, which may create a signifi cant hazard if not correctly managed. A system of automatic dilution doors is employed to mitigate this risk. This paper describes the evolution of the system and gives some examples of its eff ectiveness."

Jun 1, 2012

By P Gilroy

In recent technical investigations that were triggered from ore for rail shortfalls at Yandi, BHP Iron ore has identified a gap in resource knowledge relating to geo-metallurgical characteristics that predict materials handling performance and throughput. Within these investigations BHP has learnt that this lack of resource knowledge has translated to a lack of predictability associated with mine planning inputs which has resulted in poor compliance to plan and deviation management practices. A business value chain was developed in an attempt to identify the best possible solution to unlock this resource knowledge in the short, medium and long term planning horizons. A fast fail approach was taken with the implementation of hyperspectral blasthole analysis, which was chosen to deliver the best possible value driver for the asset. This report will detail the Yandi journey in expanding the hyperspectral and geo-metallurgical value chain, unlocking resource knowledge along the way. CITATION: Gilroy, P, 2018. Development of an empirical geo-metallurgical model that unlocks value of the mineral resources at Yandi Mine, in Proceedings Complex Orebodies Conference 2018, pp 85–87 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

By N Strong

Cracow is a high-grade; low-tonnage underground gold mine located approximately 500 km north-west of Brisbane in Central Queensland. It is a steeply dipping, narrow vein, epithermal gold and silver deposit that is accessed via a decline from surface. Cracow is owned by joint venture between Newcrest Mining (70 per cent) and Sedimentary Holdings (30 per cent). The orebodies are 5 m wide on average and the ore is extracted via sublevel open bench stoping. Stopes are extracted to a strike of approximately 25 m before being backfilled with waste. Prior to the introduction of electronics, the mine would remove a small amount of the previous backfill out to create a void, and then begin blasting two to three rings at a time, with the ore being extracted between each blast. This method caused the ore to be blasted onto the waste backfill resulting in dilution of the high-grade ore. It also meant that the extraction of each stope took a number of weeks and numerous blasting events. In the fourth quarter of 2005, the mine struck a geotechnically sensitive stope, where all 20 rings had to be extracted in a single shot or risk possible geotechnical problems that could sterilise the ore. Due to the limitations of NONEL« delay detonators the mine could not fire all the rings in a single shot and needed to use an electronic detonator system to extract the stope. Some unexpected benefits to the mine were increased fragmentation, reduced vibrations, reduced dilution, improved efficiency and improved hanging wall and footwall conditions. After the success of this first electronic shot, the mine has since moved to firing all their stopes with electronic detonators. With electronics the mine has been able to fire much larger blasts, and has in fact moved to firing their blasts in the opposite direction, firing towards the draw point instead of into the waste backfill, thus reducing ore dilution.

Jan 1, 2008

By B McCarthy

Mining has been typified of late as a boom and bust, cyclical industry operating against a steady decline in the size and quality of mineral deposits. Decreasing deposit grades and increasing costs of traditional mining techniques, all in the face of another commodity downturn, are forcing mining companies more than ever before to seek out new and innovative ways to operate. New technologies are emerging to model, control and track resources through the mining value chain, to move material about mines more efficiently, and to identify and separate ore from gangue early in the extraction process.Discovering such technologies however is only the first challenge for mining companies. Actually implementing technological change successfully has proved to be an even bigger challenge. Like for many industries, fulfilling the promised benefits for the expense and timing envisioned, has not been easy when innovative technologies are introduced.Citing the author’s insights and experiences in a number of emerging technologies, this paper explores barriers to implementing technological change in the mining context. Key elements of a change management framework, first developed for implementing mine management systems, are described to give mining executives insight into how they and their organisations can succeed through technology-driven change.CITATION:McCarthy, B, 2016. Successfully implementing technology-driven change in the mining environment, in Proceedings International Mine Management Conference, pp 89-104 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By S Szylkarski, D N. Graham

In mining, water management is an operational necessity, requiring planning and detailed engineering, as well as risk assessment. Yet, the hydrology of streams and aquifers typically extends well beyond the boundaries of mine operations and intersect with environmental and social values. Mine managers often plan, design and assess the impact of water management activities (such as dewatering, excess water disposal and flood management) with a mine site or process specific focus. The challenge is that the impacts are spatial, long-term and complex – and may be cumulative across multiple mine sites. Further, there is usually little consideration of the feedbacks and interactions between surface water, groundwater and catchment hydrology. Failure to understand these processes can lead to poor decisions and increased costs. This presentation outlines an approach to simulating integrated hydrology in mining catchments that addresses the shortcomings of traditional modelling techniques.CITATION:Graham, D N and Szylkarski, S, 2016. Simulating integrated hydrology in mining catchments from planning to closure, in Proceedings Life-of-Mine 2016 Conference, pp 101–105 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By M Andrew, H Reynolds, R Mills

As the global mining industry continues to grapple with ‘black swans’ (high consequence / low frequency events) for health, safety and environmental losses, the focus is shifting from risk assessment of these events to risk management using selected purposeful controls that reduce the risk.Fundamental to critical control management (CCM) is a soundly based rationale for selecting the right controls for each and every risk. The approach should be based on a thorough understanding of the dynamics of the event: What causes it? How frequently will it occur? How likely is the consequence to be realised? This is typically done through a bowtie and methodical numerical risk analysis. Core to this step, then, is the structure and content of the bowtie; specifically, the analytic architecture that is used to construct the bowtie. Different architectures yield different constructions, and bowties are no different.Although bowties for operational health and safety (OHS) hazards appear to have a common architecture, they are not generic. It is important to stress that they contain site specific information, are prepared by site based operational teams, and vary from site to site to reflect each site’s operational conditions. They are often a product of the knowledge and understanding of the operational teams involved, may be prone to human error, and potentially miss latent hazards that may have been embedded early in the planning, design or construction phase of a mine or facility, or within the mining equipment. Overcoming these deficiencies through constant re-evaluation of the risks, and challenging the content on the bowtie will help to minimise the chance that something will be missed.This paper will cover key themes in bowtie architecture, introduce the concept of barrier models for high consequence event (HCE) bowties and present a relevant case study to illustrate the issues that determine quality in bowtie construction and critical control (barrier) selection and management.CITATION:Mills, R, Andrew, M and Reynolds, H, 2016. Can we stop a black swan breeding? Advances in bowties and critical control management, in Proceedings International Mine Management Conference, pp 105-114 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

By Aspinall T. O

Draglines have found wide application in strip mining coal seams down to 60m depth. A research Project funded through NERDDC has been underway during the past two years investigating the application of large draglines loading overburden into hoppers feeding into conveyor systems or off-highway trucks. This paper presents the preliminary results of these investigations and covers overburden characteristics, bucket spotting con- trol, bucket design, conceptual hopper systems, system application at representative mine sites, and broad process comparison. The studies have initiated new concepts in the extended use of draglines at deeper strip- ping depths. Alternate arrangements for dragline bucket rigging and bucket control aspects of dragline stripping operations offer productivity improvements. Extended use of existing draglines includes, draglines dumping into hoppers which feed large trucks or conveyors, trigger dump buckets rigging arrangements, and rear dump dragline buckets with integral grizzly bars. The paper details these suggestions, and points to specific areas where the most productive applied research is anticipated. Mine planning considerations detail the factors involved in selecting dragline bench heights in association with hopper operations.

Jan 1, 1989

By L Sandery, S Light

Within 22 months of commencing decline development, the Prominent Hill Ankata Underground Project achieved its full production rate of 1.2 Mt/a.In 2010 construction of the Ankata Underground Project was approved. Decline development commenced in November 2010 and the turnout for the first sublevel was reached by August 2011. The first stoping ore was produced in the first quarter of 2012 and production was successfully ramped up to full production during the third quarter of 2012.Diamond drilling commenced in October 2011 and was conducted concurrently with the underground development. This presented challenges as mining and production targets had to be balanced with underground exploration activities. To achieve production on schedule, without adversely affecting the diamond drilling program and future development, meticulous and adaptive planning techniques were required. This included involvement from engineers, geologists, underground operators and underground diamond drillers.The granularity of these planning techniques allowed the management and prioritisation of development and diamond drilling down to an almost hourly basis. A constant flow of information from drill assay results was fed back into the planning systems. This resulted in a constantly evolving mine plan as the orebody was further refined. High priority areas were identified and targeted to allow continued development and a successful rapid ramp up to full production.CITATION:Sandery, L and Light, S, 2014. Managing the diamond drilling interactions in commissioning the Ankata underground mine, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 75–80 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

By Sweet I. P

Stratigraphic correlations across the Mur- phy Tectonic Ridge are crucial to regional corr. elations between the Mount Isa and McArthur River areas. Recent work in the Westmoreland and surrounding areas has substantiated the earlier general correlations between the Mount Isa and McArthur River sequences. The Mount Isa and McArthur Groups, and their equivalents, remain prime prospecting targets for major lead-zinc deposits of the Mount Isa and R.Y.C. type. A prospective area for Redbank-type copper mineralization is suggested.

Jan 1, 1974

As world demand for various minerals increases the mining industry in its endeavour to satisfy this demand will, eventually,look to the extraction of orebodies which previously may have been uneconomical to mine. These orebodies may be of two types. Firstly, new low grade orebodies and secondly, remnant sections of previously mined orebodies. Some of the factors relative to remnant mining operations are discussed and the potent- ial of remnant mining in providing an important contribution to future world metal production is considered.

Jan 1, 1975

By N McKay, J Vann, W Ware, P Hodkiewicz, C Morley

"Geometallurgy is now recognised within the mining industry as an approach that can both maximise value and reduce the risks associated with resource development. The process of spatial ore variability testing for metallurgical response and the use of quick, inexpensive metallurgical proxies has been well developed in the past decade in industry and the literature, and via various collaborative research programs and laboratories. Technology continues to advance with new techniques such as hand-held analytical tools and automated hyperspectral core scanning, allowing for even faster, less expensive in situ geometallurgical testing.In the current mining industry downturn, a critical frontier of geometallurgy is in its application in short-term geological modelling (ore control) and mine planning, and the associated decision-making. This is the end game at which the hard-won knowledge of orebody variability can be exploited to add near-term value. In order for spatial block models to be fit-for-purpose for such tactical uses, they must be populated with key geometallurgical information and then have workflows that use this richer model as a basis of material allocation to destinations so that the true value of the resource is realised.We envision geometallurgy (geomet) programs designed to add and sustain value at two levels:‘Strategic geomet’ has a long-term strategic focus that actively uses all relevant data that helps predict processing performance such as bench-scale metallurgical tests, mineralogy, geochemistry, ore texture etc (‘the geometallurgical database’) to model spatial ore variability and metallurgical response throughout the life-of-mine (LOM). This will enable better resource definition, more optimal mine planning and scheduling, improved process design and sustaining capital strategy over the LOM. The value-realisation is gained by basing all these strategic decisions on spatial models that better reflect the actual value of blocks (or aggregates of blocks) in the model.‘Tactical geomet’ has a short- to medium-term tactical focus that, again, actively uses the geometallurgical database, but also includes new data derived during ore control activities (such as drilling and sampling) to inform allocation-to-destination decisions via the ore control process. This will enable improved efficiency (ie less error) in allocation of mining blocks as direct feed, stockpile or waste. Importantly, this efficiency will be measured in terms of value and not grade, which is an incomplete – and typically biased – proxy for value. The key benefit is that ore control will then be planned and executed on the basis of realised value.We therefore propose a twofold systematic and holistic, value-based geometallurgical process. This process needs to be planned and implemented in an integrated manner, noting that strategic and tactical geometallurgy can be worked on by the same professionals, sharing data, methodologies and potentially models. What differs between the two levels is the required granularity, the business context and (critically) the decision-making time horizons.CITATION:McKay, N, Vann, J, Ware, W, Morley, C, Hodkiewicz, P, 2016. Strategic and Tactical Geometallurgy – a Systematic Process to Add and Sustain Resource Value, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 29–36 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By R Ballantyne, M Adams

Time Usage Models, used as a basis for calculating performance indicators for mobile mining equipment, have developed from very simple to very sophisticated models. This development has paralleled the increased collection and analysis of production data that itself has been enabled by the evolution of underground voice and data communications along with the relevant information systems. A Time Usage Model divides the hours that equipment is (or is not) used into standard components, by a hierarchical breakdown, so that measures of productivity can be used to compare performance of both people and equipment. The calculation of equipment availability, and thus the underlying Time Usage Model, has always been an extremely emotive topic as different groups use time usage information for different purposes. The direct link between measuring performance Key Performance Indicators (KPI) calculated from these models and employee rewards impacts upon the workforce. This paper discusses the conflict in use by various stakeholders and proposes ways to address some of the more contentious issues each supported by case studies. The simple status code functionality used by early systems has proven inadequate, leading to the evolution of “work-arounds”. These workarounds have become the norm and unfortunately have become embedded in the next generation of models and the information systems that incorporate them. This paper contends that the industry should stop building Time Usage Models to accommodate shortcomings in proprietary systems, but rather collaborate with suppliers to develop innovative methods to deal with the fundamental requirements. There are many points of differentiation that are not clear-cut. Pitfalls are discussed as well as threats to success. A framework of rules is developed as guidelines for how a Time Usage Model should be developed and applied. This will hopefully stimulate the on-going discussion as to how Equipment Availability and other components of the model should be calculated.

Mar 15, 2021