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By Grant Buma

Groundwater restoration is an uranium leaching. Information on the technology, costs, and the current permitting regulations is of vital operators and to firms considering in important aspect of in situ effectiveness of the current state and federal government importance to in situ leach situ leaching. This study, funded by the U. S. Bureau of Mines, describes: (1) all recent restoration attempts at commercial in situ leach operations, (2) restoration costs reported by the industry, (3) empirical equations that predict the amount of groundwater flushing required to meet the current restoration criteria, and (4) in situ uranium permit requirements for the states of Texas, Wyoming, New Mexico, Utah, Montana, Colorado and South Dakota, and Federal requirements.

Jan 1, 1981

By S O. Hille

Modern remote mining operations in Australia are more commonly trending towards fly-in/fly-out (FIFO) sites. This trend is driven by numerous factors including increased business centralisation, reduction in operating costs, and a desire to live in coastal cities that offer closer family networks and a greater diversity of facilities. Consequently, the resource development industry has had to adapt. When WMCÆs Mount Keith Nickel Operation commenced operations in 1994, it was developed as FIFO for its entire workforce. Since then, there have been several permutations of rosters within a 21 day compressed work cycle including the 14/7 cycle. This paper discusses a case study of the change in management process to the 9/5 work cycle focusing on minimising fatigue in the workplace. It includes the discussion of the business case, employee reaction and the practical application. The impact of the best practice change after 18 months is discussed.

Jan 1, 2002

By B Beale

Bow-tie analysis is a commonly used tool to identify and display risks that have the potential for an undesired hazardous event. The output of the analysis are bow-tie diagrams, which are an effective and versatile communication format that can be applied to any type of risk. Contrary to their simplicity, a proper bow-tie diagram that maintains its usefulness and clear communication is difficult to build. Over two decades assisting Major Hazard Facilities with bow-tie analysis for Safety Cases, several common mistakes have been identified. This paper aims to highlight those issues with examples and provide improvement strategies. A sample of the most common mistakes are: - overly complicated risk analysis - poorly scoped and defined terms - poor descriptions and justifications - identifying too many dependent controls. Overly complicated risk analysis leads to wasted time in obtaining data for little gain. The bow-tie diagram is only a model. Effort should be redirected into identifying and managing controls that will make a tangible difference to site risk. Broad scopes lead to enormous and confusing bow-tie diagrams for both the user and the workshop team. Defining the scope of the study, the consequence severity of interest and critical control characteristics creates focused workshops and targeted analysis. With more definitive scope, there may be more bow-tie diagrams, however, they are succinct and specific. Well described causes are imperative for clear communication to users, regulators and future bowtie review workshop groups. It is best to use common wording structures and explain the event stepby- step. Also, clearly document any likelihood calculations and use data references where applicable. Identifying all possible controls creates a false sense of security that there are many layers of protection. In reality, most controls are dependent on a single system or person and could all be compromised from a single failure. A definition of a ‘bow-tie’ control is required whereby it must be independent from other controls. Improving the bow-tie analysis process will assist operators in developing meaningful and ‘operational’ bow-tie diagrams to support risk management systems and practices.

Apr 16, 2024

By H Jones

Closure cost estimates may be generated at any stage of a mining operationÆs life; commencing with the initial prefeasibility studies and continuing through to the final decommissioning cost estimates. However, not all mine closure cost estimates are necessarily the same. Cost estimates will vary depending on the purpose for which they are prepared, the organisations requiring or undertaking the estimate and the stage of the mining operation. Different organisations can legitimately arrive at disparate cost estimates for closing the same mine because the organisations have different reasons for requiring the estimates. Another, equally valid, reason for potentially wide variations in cost estimates by different organisations on the same mine site is the different definitions of æclosure costsÆ used by different estimators. This paper considers the different approaches by different organisations including operating companies, government authorities and financial organisations and uses a hypothetical example based on practical experience to illustrate some of these differences in estimation methods.The paper suggest that a more consistent approach to closure cost estimating in the Australian mining industry would assist mining companies, governments, the accounting industry and the broader community to better understand this complex component of mine planning. One possible approach to closure cost estimating is briefly outlined.CITATION:Jones, H, 2012. Closure cost estimation - All things to all men?, in Proceedings International Mine Management 2012, pp 115-124 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012

By Aaron Nickoli, Brad Clark, Thomas Horan E. I. T.

The Canal Road Dip Slide is an active landslide located on South Pender Island, British Columbia. The effects of the fall 2021 atmospheric river prompted the British Columbia Ministry of Transportation and Infrastructure to initiate an emergency response project to realign Canal Road out of the active landslide zone for safe traffic passage. The work was tendered in a bidding process and included blasting and rock excavation work at the project site. Tetra Tech Canada Inc. was retained by the contractor to be their Blast and Vibration Specialist. The close proximities of an active landslide, a Canadian National Park, and other segments of construction posed stringent constraints to blasting. The governing constraints to blast design included a Peak Particle Velocity (PPV) limit of 3 mm/s (0.12 in/s) along the adjacent landslide centerline and a slide movement constraint. Sixteen blasts were executed throughout the scope of work to remove 2595 m3 (3394 yd3) of meta-sedimentary rock. Blast designs adhered to the constraints by utilizing up to quadruple decking in 50+ blast holes which lead to complex timing schemes. Several blasts were over 4 seconds in duration, with one at nearly 8 seconds. The landslide area was monitored with Shape Accel Arrays (SAA) throughout the scope of work that tracked geohazard slide movement during construction. The SAA data is presented, and the effect of blasting is discussed. Site specific parameters for PPV estimation were calculated and are presented. Collaboration and communication between the stakeholders allowed the project team to successfully overcome the technical challenges posed by the Canal Road Dip Slide.

Jan 26, 2026

Jan 1, 1989

By J Missen, P Currie, J Bohan, D Clark

AGL is one of Australia’s leading integrated energy companies and the largest ASX listed owner, operator and developer of renewable energy and thermal generation in the country. AGL owns and operates the 2210 MW Loy Yang A power station and adjacent 30 Mt/a brown coalmine in the Latrobe Valley, Victoria. It also supplies coal to the nearby 1050 MW Loy Yang B power station owned by the GDF Suez (Engie)/Mitsui partnership. The mine is currently nearly 5 km long, more than 2 km wide at the operating face and up to 200 m deep. AGL employs a large workforce at Loy Yang and a substantial amount of services are performed on-site by contractors and consultants.GHD provides mine planning, earth sciences, civil/geotechnical engineering, dam surveillance, plant engineering and environmental services to AGL Loy Yang through an alliance framework. GHD is one of the world’s leading professional services companies operating in the global markets of water; energy and resources; environment; property and buildings; and transportation. In addition to GHD’s global footprint, the company also has a significant Victorian presence, including a permanent, well-resourced regional office in Traralgon, approximately 10 km from Loy Yang, as well as a permanent site office.A joint paper on the Loy Yang mine professional services alliance model was written for the AusIMM International Mine Management Conference in 2006 by Woods and Wood. Now ten years on, this paper provides an overview of the present relationship and arrangements, including the continued transformation of the alliance model and maturing of the relationship contract.These are challenging times, with increasing cost and regulatory pressure driving change in the broader energy and resources industry, and locally including both the mining and power sectors at Loy Yang. Flexible models to achieve a balance between internal personnel and access to key external skills, whilst achieving value for money and transparency, is increasingly critical. The right drivers and performance measures are essential, particularly when confronted with potential major technical and environmental risks (considering significant ground failure and fire events that have occurred elsewhere within the Latrobe Valley over the last decade) within a sector that is reducing costs and optimising production.This case study discusses the alliance status and changes, reasons behind adjustments and what the future is likely to hold. The paper also explores the validity of the original objectives and the extent to which they have been achieved. The philosophy of the alliance is to continue closely aligning the objectives of the two companies in the best interests of the Loy Yang site and immediate surrounds/stakeholders. Quality of service, costs, timeliness, health and safety (H&S) and some operational activities (aquifer depressurisation) remain important aspects and are reflected in key indicators for which performance is measured.CITATION:Clark, D, Bohan, J, Currie, P and Missen, J, 2016. AGL energy, Loy Yang and GHD – a further case study in alliancing: ten years on, in Proceedings International Mine Management Conference, pp 321-330 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 22, 2016

High resolution seismic refraction tomography has proved to be a useful tool to effectively estimate depth of blast induced damage in a mine face. Excavation blast damage can be as shallow as 1 to 2m and requires resolution at a fraction of a meter for effective imaging. We used an accelerometer with flat frequency response to 1000Hz to record data at spacings of approximately 0.25 to 0.5m along mine walls. First arrival times from the seismic data were used to produce P-wave velocity tomograms. The tomograms show transition from low velocity zones to velocity associated with competent rock. We interpret the low velocity zones to indicate residual fracturing from blasting. Experiments on a concrete test block and at two underground mine locations give results that are consistent with fractured rock transitioning to competent rock. Our method can be applied efficiently in an underground environment to provide continuous velocity information with depth into a mine wall over a span of approximately 10m.

Jan 1, 2009

By W. N. Hoskins

This report covers the final results of a two-phase contract study conducted between July 1974 and October 1976. A comprehensive summary of the initial phase of the study is included. Phase I of the study involved the investigation and evaluation of all potential candidate underground systems for mining the deeper deposits of oil shale and associated minerals in the Piceance Creek basin of northwestern Colorado. Phase II called for the refinement and the detailed technical and economic analysis of the most promising system or systems, thus disclosed. Of the several systems initially investigated and evaluated, four Showed considerable merit for exploiting the deeper deposits: (1) chamber and pillar mining with spent shale backfill, (2) sublevel stoping with spent shale backfill, (3) sublevel stoping with full subsidence, and (4) block caving mining using LHD's. Final refinement and analysis of these four systems indicated their technical feasibility over at least part of the range of conditions expected in the deeper deposits. Their economic feasibility also was indicated under certain operating and market conditions. A variety of engineering, production, and cost information is provided on each of these systems.

Jan 1, 1976

By William J. Almas

Operating uranium mill tailings containment and mill decommissioning activities are regulated by the Nuclear Regulatory Commission (NRC) and the Environmental Protection Agency (EPA) through numerous regulatory mechanisms. Reduction of radon emissions from tailings disposal areas, remedial actions to return groundwater to baseline constituent concentrations, and 200-to 1,000-year stabilization of tailings are major focus areas of regulation. The cumulative economic impact and uncertainty associated with regulation are very significant and will hinder future development of uranium milling facilities.

Jan 1, 1991

By G. Beckstead, L. Gormely, R. Zimmer, K. Hanneman, B. Nethery

As part of the EIS and permitting activities for the Pogo Mine in Alaska, a risk assessment study for the water management plan was carried out. The basis for the study was a site water volume and contaminant balance model. Probabilistic modeling was carried out using the @Risk Monte Carlo simulation package to investigate the frequency, quantity, and quality of discharges under varying assumptions. The results were used in discussions with regulatory officials as part of the permitting process for the project. The simulation allows probabilistic modeling of key environmental parameters based on input frequency distributions involving both quality and quantity of flow. When combined with predictions of water treatment plant capacities and removal efficiency, this was very useful for defining the likelihood of important regulatory outcomes. Based on the model, certain project modifications were made. Using the simulation as a basis, ongoing dialog with regulators led to consensus that all potential risks have been considered and mitigated for the Pogo Mine according to their likelihood and severity, and that regulatory requirements would be achieved. The paper describes the model and some of the applications for which it was used.

Jan 1, 2005

By P. Michael

Proponents of geomorphic mine land reclamation have criticized current reclamation practices in the coal fields of steep-sloped Central Appalachia as too narrowly focused on civil engineering principles and neglectful of the functional and aesthetic benefits of reclaiming mine sites in ways that mimic natural landforms and drainage patterns. They observe that current mining and reclamation practices are radically transforming the mountain-and-valley terrain into gigantic flat plateaus and, in doing so, disrupting the beauty and ecology of the natural landscape. Instead of designing and constructing linear or planar surfaces and unvarying slope gradients during the reclamation process, they recommend ?landforming,? i.e. the adoption of curvilinear, compound slope forms that blend well with the surrounding physiography and represent the result of naturally stabilizing geomomorphic processes. The authors feel that the concept of geomorphic mine land reclamation is sound, however, its application to the Central Appalachian coal fields faces significant--albeit not insurmountable--challenges. They include: (1) existing reclamation enforcement regulations that are focused on civil engineering principles and not explicitly supportive of geomorphic methodologies; (2) regulatory agencies? current intent to limit the down-gradient reach of excess spoil fills in order to allay disruption or burial of natural streams; (3) actual or perceived increases in reclamation costs; and (4) the challenge of designing and constructing ?natural? landforms that are mature and stable in an otherwise youthful, erosional landscape.

Jan 1, 2010

By James J. Gusek

The Atlantic City iron mine is located in Fremont County in central Wyoming, near the historic gold mining camps of Atlantic City and South Pass City. The mine lies on the southeast flank of the Wind River Mountains at an elevation of about 2,470 m (8,100 ft) above sea level (Fig. 1). An 81-h M2 (200-acre) tailings impoundment at the Atlantic City taconite operation has been a source of blowing dust. The site qualified for reclamation under Wyoming&apos;s Abandoned Mine Land (AML) reclamation program. The ultimate reclamation construction incorporated commercially available organic amendments and fertilizers into a 300-mm- (12-in.-) thick cap of a sterile clay loam cover material. The water level was lowered in an adjacent flooded mine pit that was feeding uncontrolled seeps into the tailings basin. A wide tailings pond spillway was built that allows flood control while minimizing seasonal water-level fluctuations in the pond. Rock berms and rock snow fences were built for wind-erosion control and soil-moisture preservation. Future work includes tree planting in the protective wind/ snow shadows of rock berms and rock snow fences and plugging a decant pipe. US Steel opened the Atlantic City iron mine in August 1962. It closed in 1983. Taconite iron ore was mined by surface methods. The ore was magnetically separated from the waste. The magnetic concentrate was mixed with bentonite, formed into pellets and roasted to produce a blast furnace feed stock for US Steel&apos;s blast furnaces in Geneva, UT. The pellets were hauled by rail to the Geneva Iron Works. The Atlantic City Mine produced three types of wastes. These included waste rock overburden from mining, a coarse-grained (sand to small-gravel sized), nonmagnetic reject rock termed "cobbs" and fine-grained tailings ranging from 600 to 75 µm (28 to <200 mesh). The waste rock has been used as an aggregate/rip rap source by a local contractor and the Wyoming Department of Transportation (WYDOT). WYDOT also

Jan 1, 1998

When studying minerals degrees at university, all the emphasis is towards sending the graduates into the bush to work at a remote mine; however, that is not the only option available to new graduates. There are positions in equipment supply companies, commercial laboratories, research organisations, engineering companies and contractors of many types. The aim of this paper is to show metallurgy graduates that there are non-mine site based career options available to them that offer outstanding career development. This is illustrated by outlining the research being undertaken by Magotteaux Australia and by telling the story of a graduate metallurgist working in MagotteauxÆs small research group. Magotteaux is an international supplier of grinding media and wear resistant components for the mining industry. The Australian research group is focused on determining the effects that the choice of grinding media has on subsequent processing, for example flotation and leaching, by using newly developed tools and techniques.

Jan 1, 2006

By S. Sinha, S. Ganguly

"In an opencast mine explosives are used for fragmentation of rock. Inefficient use of explosive energy in an opencast operation produces excessive ground vibration, which is measured by peak particle velocity (PPV). To mitigate ground vibration, it is essential to develop a model to predict PPV. At present empirical models are used. These models are based on only a few input variables, hence they fail to take into account the effects of the myriad factors that cause ground vibration. Due to lack of explicit knowledge about the complex mine blasting system the scope of application of mathematical and statistical modeling techniques is limited. The artificial neural network (ANN) technique is a learning algorithm that can remove some of these limitations and can be applied to predict PPV. In this paper an ANN model is developed for prediction of blast vibration using 248 data records collected from three coal mines with diverse geomining conditions. The correlation coefficient between measured PPV and model output was found to be 0.96 and the average error percentage 11.85. The ANN model output was compared with the output of three empirical models that are widely used for prediction of PPV. The correlation coefficient between the PPV predicted by an empirical model and measured PPV data was 0.63 and the relative error percentage 38.47. This result demonstrates the superiority of the ANN model compared to empirical blast models. By using site-specific structural discontinuities as input the model performance can be further improved. Sensitivity analysis and 3D plotting were used to gain further knowledge about blast-induced ground vibration. IntroductionIn an opencast coal mine explosives are used for fragmentation of coal and overburden. If the explosive energy is not fully utilized it causes blast-induced ground vibration, which may damage nearby structures. Ground vibration is expressed as peak particle velocity (PPV). During different stages of mine planning and operation, it is necessary to use a ground vibration prediction model for blasthole design. Selection of the modelling technique is crucial. Mathematical and statistical modelling techniques have limited application because of the lack of explicit knowledge about the complex mine blasting system. Vogiatzi (2002) highlighted the problem of multicollinearity in case of statistical modeling techniques. Mutalib et al. (2013) stated that mathematical models are unable to capture the nonlinear relationship between several blasting-related parameters due to the complexity of the model input data. However, the difficulty involved in modelling complex blast vibration problems can be removed by adopting an alternative soft computing modelling approach. One of the soft computing techniques is the artificial neural network (ANN). Ragam and Nimaje (2018) developed an ANN model for predicting PPV using six input variables. Kosti et al. (2013) stated that the conventional predictors fail to provide acceptable prediction accuracy. They showed that a neural network model with four mine blast parameters as input could make significantly more accurate on-site predictions. Sayadi et al., (2013), using a database from Teheran Cement Company limestone mines, found that a neural network resulted in maximum accuracy and minimum error. Khandelwal and Singh (2009) developed an ANN model using 150 data records from an Indian coal mine with site-specific rock characteristics and geomining setting. Khandewal and Singh (2007) built a ground vibration prediction model for a magnesite mine using four prediction variables with 20 data records. Kamali and Ataei (2010) predicted PPV in the structure of the Karoun III power plant and dam using an ANN. El Hafiz et al. (2010) evaluated ground vibration predictors using data from a single-station seismograph at a limestone quarry in Egypt."

Feb 1, 2019

By M Mee, R L. Gwyther

Accurate measurement of rock mass response during the mining of massive underground orebodies is essential, as mines become larger and deeper. These measurements enable: provision of quantitative data for optimal pit slope design and engineering; monitoring of the stability of deep pit slopes, the long-term integrity of shafts and large-scale underground infrastructure, and long-term measurements of deformation or rock mass creep following the mining process for environmental management. Strainmeters traditionally used for deformation measurement have neither the long-term stability nor the high sensitivity to perform measurements in these applications. This paper describes a new precision borehole strain monitoring system (GTS) currently deployed by CSIRO Exploration and Mining, which has the potential to solve these new issues in rock mass deformation monitoring. This technology was originally developed for use in hard rock mines (Gladwin, 1977) and refined considerably for earthquake research (Gladwin et al, 1994; Gwyther et al, 1992). A case study of the use of the GTS in monitoring longwall coal mining over the period 1993 - 1998 is presented.

Jan 1, 2000

By Jr. Denton

This U.S. Bureau of Mines report presents the documentation for HEAPREC, a methodology for calculating reclamation performance bonds for cyanide heap leach operations. HEAPREC is a template developed for use with Lotus 1-2-33 release 2.01 or newer software. The report is presented in step-by-step "user&apos;s manual" format. Appendices contain detailed background and reference material on performance bonding, cyanide detoxification regulation, cyanide detoxification methods, general mine reclamation procedures, and an example bond calculation.

Jan 1, 1992

By Don Deardorff, Ke Yang, Yingcai Han, Ken Sorensen, Robert Kruger, Mark Petersen, Diane Fiorelli, Larry Goldfarb, Kathryn Petek, Kwabena Ofori-Awuah

Design of deep foundations for lateral loads requires an understanding of soil-foundation-structure response during loading. Lateral loads on a deep foundation (piles) could be due to earthquakes, winds, waves, and/or machine vibrations. Over the years, analysis of response of piles due to lateral loads evolved from closed-form solutions to p-y methods to strain wedge to finite element/finite difference modeling. Although analysis of lateral response of piles and shafts is routinely performed, there is no single guidance document and/or standard for design and testing. Several different analytical methods are available for the analysis, and the resulting design can result in significantly different responses which can create confusion. This is especially true for analyzing and designing piles in potentially liquefiable soils with lateral spread issues under seismic conditions.This guidance document is intended to assist geotechnical engineers, pile designers, and contractors in analysis, design, and testing of piles and drilled shafts for lateral loads. This document discusses the background of different analytical and testing procedures and presents the recommended methods for analysis, design and testing of piles for lateral loads.Chapter 1 defines the different kinds of lateral loads to which a single pile or pile group may be subjected. This first chapter also presents different types of piles used to resist lateral loads.Chapter 2 discusses geotechnical issues related to lateral pile design such as liquefaction and lateral spreading and other non-seismic issues. Also addressed in Chapter 2 is geotechnical site characterization (as related to lateral loads) in terms of site investigation, in-situ testing, geophysical testing, laboratory testing, and estimation of soil/rock properties.Chapter 3 discusses the background and available analytical methods and tools for the analysis and design of single piles and drilled shafts. Several methods of analyses from closed-form elastic solutions to the finite element/finite difference solutions and their applicability are discussed. Available commercial computer software packages for analyzing single piles and drilled shafts are also presented.Chapter 4 expands the discussion of single piles and drilled shafts into the analysis and design of pile groups. In addition, group effects, resistance of pile caps, results of previous experimental and analytical studies, and available analysis tools and software for pile groups are discussed.Chapter 5 presents the issue of lateral resistance of piles and drilled shafts as discussed in different national and international building and non-building codes. A summary of extensive research on several codes are presented to facilitate the compliance with different codes.Chapter 6 discusses structural design issues of individual piles and drilled shafts such as depth of fixity.Chapter 7 discusses soil structure interaction issues related to kinematic and inertial effects due to seismic loading and available methods of analyses.Chapter 8 discusses and presents the typical procedures for the lateral load testing of piles. This guideline was developed as an aid to the practicing engineer in providing information, direction and commentary on the lateral design of deep foundations. Although all reasonable effort has been made to accurately compile the material and information contained herein, no warranty is made with regard to any such material or information and the Deep Foundation Institute assumes no responsibility for any possible errors or any direct or indirect result of the use of any such material or information. It is not intended that this document address every factor affecting lateral design for every situation. Therefore it is the responsibility of the person utilizing information from this document to confirm that it is appropriate and correct for their situation as well as to understand and properly apply

Jan 1, 2012

By Jonathan K. Hrica, Brianna M. Eiter

The ability to identify hazards during a workplace examination is a critical skill for mineworkers to have in order to maintain a safe workplace. While research suggests that being able to successfully recognize hazards requires a complex set of competencies, it is unclear which competencies are most critical to adequately perform a workplace examination. This paper presents a hazard recognition competencies framework as an explanation of the competencies that affect mineworker hazard recognition. To better understand how the industry is selecting and preparing workplace examiners, researchers fromthe National Institute for Occupational Safety and Health (NIOSH) interviewed nine health and safety (H&S) professionals at surface stone, sand, and gravel mine sites throughout the USA. A primary purpose of these interviews was to verify the competencies included in the hazard recognition competencies framework and to understand why these competencies are critical. Finally, the results of this study are presented within the context of current NIOSH research findings related to hazard recognition.

Jul 27, 2020

By Leslie F. Sawatsky

Raw water import requirements for oils sands mines depends mainly on factors such as ore processing rate, ore material characteristics, tailings processing technology, tailings storage systems, process water storage operations, the phase of tailings production, and non-recoverable seepage losses from tailings ponds. These factors can be readily quantified to calculate raw water import needs. Nevertheless, mine water balance continues to be misunderstood by some regulators, stakeholders and possibly even mine operators. Confusion over consumptive uses has led to a focus on recycling which is not necessarily applicable to a closed circuit water management system. Some water conservationists focus attention on raw water intake rules instead of the technical decisions that control consumptive uses. Typical oil sands mine water balances for various types of tailings operations, are analyzed to illustrate the effect of controllable and uncontrollable parameters as well as major options that need to be explored for reducing water demand. Uncontrollable parameters including tailings fines content, oil content of ore, connate water, mine depressurization water inflows and surface water hydrology. Controllable parameters include storage operations, advance water supply ahead of mining operations, type of tailings operation, net tailings pond seepage losses, and tailings impoundment operations. Potential reductions of raw water supply rates may be obtained by providing greater on-site storage to attenuate fluctuation in water demand, advance water accumulation prior to mine start up, early commencement of CT operations, thickened tailings disposal and paste technology. Water conservation measures should be focused on reducing on-site process water storage and water content of tailings material.

May 1, 2004