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By Murray Wood, Michael Schaffer, Makat Katom

"An expert system applied to the control of mineral process unit operations is, by its nature, the site best operating practice, having been designed by the local experts in conjunction with consulting metallurgists. The “common sense” layer in a MET (MinnovEX Expert Technology) solution determines an appropriate action for the current operating conditions through a developed heuristic model of the process (expert system). The magnitude of the setpoint change that is made is proportional to the confidence that the system has in its interpretation of the current conditions (fuzzy logic). The solution is always striving to take the process to a constraint and thereby optimise the operation. An accepted limitation of the solution is that the only way the system can determine if a constraint has been reached is to exceed it and then withdraw – essentially “experimenting” with the process. By leveraging a model, which can accurately ""simulate"" the process, this restriction can be circumvented by pre-testing the set point change through a ""what if"" analysis and then modifying the solution as appropriate.At Ok Tedi, the introduction in 1999 of a MET expert system for SAG milling resulted in significant improvement in circuit throughput. Yet, with the additional inclusion of an accurate model of the process there was still more that could be achieved. Hence, in 2002 a MET Neural Network model was developed and deployed to enhance the existing expert system solution. The principal objective of this model was predicting the effect that changes in SAG tonnage and density would have on the power draw of the mill - essentially a power predictor. The results have seen a decrease in process variance with an associated increase in average circuit performance.This paper describes the methodology by which the Neural Network model was implemented, the considerations and limitations when applying this technology and ultimately the results that were achieved."

Jan 1, 2003

By Lyall Workman, Jack Eloranta

Blasting has an important impact on mining and milling well beyond the necessary ability to dig and load the ore efficiently. There is an increasing body of blasting research indicating significant impacts in crushing and grinding. These include increased production through higher output and fewer delays for bridging and jamming by oversize. In addition, fragmentation better suited to the crushing and grinding system is indicated to lead to reduce energy consumption by these activities, an important result in today’s environment. An important component of optimum fragmentation for this purpose appears to be micro-fracturing within individual fragments. This differs from fragmentation criteria for loading which focus mostly on fragment size. Therefore, one must analyze blasting broadly to obtain satisfactory results throughout the operation.

Jan 1, 2003

By P. He

Abstract This paper introduces tested results of rock-socketed pile in Nanjing, Wuhan and Chongqing. From a force- transfer model, a distribution of axial force for pile-body and inlaid resistance for rock-socketed pile was deduced. Comparing the results of test and calculation, it shows that the calculation result coincide with the test result. Keywords rock-socketed pile, load transfer, inlaid resistance, end resistance. Zusammenfassung: dieser text legt eine kuyze Einfuehyung ueber die Erfolge wissenschaftlicher Forschungsarbeit in bezug auf die Grundprinzipien der Mechanik von Belastungsuebermittlung der Einlegesteinpfeilers der Durch Benutzung von Ausgleich/Balance der inneren Kraft und Deformationskoordinierung wird das mechanische Modell der Belastungsuebermittlung des Einlegesteinpfeilers aufgestellt. Vom lebendigen Beispiel wird dia Wellenkraft des Steinpfeilera und die Verteilungskurve Einlegebfestigungskraft ausgelegt, man hat diess bereits mit der tatsaechlichen genessenen Kurve verglichen. Schluesselwoerter: Einlegesteinpfeilers, Belastungsuebermittlung, Einlegebfestigungskraft, Seitenwiderstand. Résumé - Le présent article décrit de façon succincte des résultats de la recherche sur le mécanisme du transfert de chargement du pieu d’ancrage au massif. Une modèle dynamique du transfert de chargement du pieu d’ancrage au massif est ainsi établie avec l’application des conditions de l’équilibre de contraintes internes et de coordination de la déformation. L’expérimentation sur des exemples réels a permis de mettre à jour des courbes de distribution de la force axiale du corps du pieu et de la force d’ancrage avec comparaison aux courbes effectivement mesurées in situ. Mots clés - Pieu d’ancrage au massif, Transfert de chargement, Force d’ancrage, Résistance à la pointe

Jan 1, 2003

The traditional measure of Lost Time Injury Frequency Rate (LTIFR) as a measure of improvement in safety performance is recognised as inadequate and misleading, lulling managers into believing that safety is improving. It is a reactive measure, and steadily declining LTIFRs around the world have failed to be accompanied by a similar reduction in the fatality rate. This paper confronts the industry with the attitudes of some mining managers, such as one that allowed fatalities to occur in the case of a gold mining company at a rate of one death per 150 000 ounces of gold produced while claiming their safety record has improved, as shown by a falling LTIFR, and viewing fatality reductions as a long-term goal instead of an immediate priority. A quantum shift in management attitudes is required to focus on proactive measurements to detect the indicators of an impending disaster, and to predict conditions conducive to fatalities. Corporate CEOs are challenged to attend the funerals of all workers killed in the workplace. CEOs who fail to attend such funerals send a message to employees that the CEOÆs priorities lie elsewhere, and that profits take priority over workersÆ lives. The dichotomy of whether mining companies are run for the benefit of shareholders or whether companies owe social responsibility to the community is examined. The role of individual responsibility for personal safety is examined, together with the psychology of employees in the mining industry. A number of proactive measurable indicators are suggested to stimulate discussion on developing robust measuring tools to predict and therefore prevent fatalities.

Jan 1, 2003

By S. G. Gendler

One of the ways of trauma and occupational diseases level reduction is noted to be the improvement of the labour protection measures planning. As an indicator for prospective trends determination in the labour protection planning improvement sphere economic risk has been proposed to be used. The trauma and occupational diseases analysis based on the correlative and regressive methods has been carried out for the “Vorgashorskaya” mine of Pechora coal basin. Trauma and occupational diseases occurrences frequency and economic losses value have been estimated. Trauma and occupational diseases economic risk distribution analysis has been presented in respect to the different subdivisions and occupational groups of “Vorgashorskaya” mine.

Jan 1, 2003

By S. L. Bell

Most Australian longwall coal mines are currently working coal faces up to nine kilometres from the surface. In the event of a mine emergency walking this sort of distance wearing breathing apparatus becomes very difficult if not impossible. Self-rescue continues to remain the focus of mines rescue in Australian coal mines and this paper describes a vehicle modification which will improve the chances of a miner rescuing himself. Existing mine personnel transport vehicles are not designed to operate in some types of atmospheres that may be present following a mine fire or explosion event. An Australian Coal Association Research program (ACARP) funded research project recently completed in Australia has developed a specification for a vehicle that is able to operate safely in some types of post emergency atmospheres. During the course of this investigation, diesel and electric vehicles were examined prior to making a final decision on vehicle suitability. Based on the fact that there are already some 1500 diesel vehicles in use in underground coal mines in Australia it was decided that modifications to existing diesel engines would be the best option. This presentation will outline the proposed specification for the vehicle and the reasons behind the decisions that were made with respect to the specification.

Jan 1, 2003

By Vladimir I. Ryaboy, Konstantin M. Asonchik

"At flotation of sulfide-barite ores of one of deposits sulfide and barite concentrates are obtained. In sulfide cycle potassium xantogenate as a collector in consumption of 200 g/ton, methylisobutylcarbinol (MIBC) as a foaming agent in consumption of 30 g/ton and also liquid glass are used. In barite cycle tall oil as fatty acid collector in consumption up to 400 g/ton is used.Sulfide concentrate represents mainly gold- and silver-containing pyrite. The contents of gold makes not less than 10 g per ton, silver - not less than 278 g/t. Barite concentrate contains up to 86% of barite.Factory is working in water recirculation conditions. Owing to that in barite cycle fatty acid collector is used, technological water from tailing repository contains fatty acids soap up to 25 mg/l. Before submission into sulfide cycle this water is conditioned with active carbon to delete the main part of fatty acid collector. The active carbon consumption makes 0,4-0,5 kg per 1m3 of water or 1,5-2 kg per ton of ore. The above mentioned consumption of active carbon improves reducing of contents of fatty acid collector from the initial concentration of 25-30 mg/l to 4 mg/l. At concentration 4 mg/l fatty acid collector does not render negative influence on flotation index in sulfide cycle. At the absence of active carbon pollution of sulfide concentrate and its irrevocable lost are observed."

Jan 1, 2003

By Kot Unrug

For the purposes of underground mine design, twelve cores of the Springfield (V) Coal (Pennsylvanian) roof and floor were retrieved. Each core was photographed, described fresh in the barrel, and the rock quality designation (RQD) was measured. Cores were wrapped in plastic and delivered to the rock mechanics lab. At the lab RQD was remeasured and new photographs were taken before running geotechnical tests including weatherability. Significant differences in barrel RQD's vs. lab RQD's have been noticed in spite of careful handling. The drill site RQD is generally used to calculate geotechnical results, but in some types of coal measure rocks, further fragmentation of core takes place with slight changes of moisture content, which occur even in well wrapped core. This creates a dilemma which RQD should be used for support design. Rocks around excavations are exposed to the significant changes in moisture content due to the seasonal weather changes and related fluctuation of humidity of air ventilating a mine. Therefore, it appears to be more realistic using laboratory RQD which corresponds closer to the actual rock condition around the excavation. Weatherability test, developed for characterization of time dependent behavior of rock exposed to fluctuations in moisture content, is thought to be related to the above-mentioned changes of RQD. In weak shales, mudstones and claystones which weather rapidly, it is essential to characterize their future behavior in the pre-mining stage. This can allow for a realistic design of primary, and particularly secondary support in coal mines, especially in coal fields where such geologic conditions exist.

Jan 1, 2003

By W. Newcomen, D. Brox

The assessment of the stability performance of open pit highwalls has traditionally been based on consideration of surface movement rates. Although generally accepted in industry, this approach presents challenges for establishing appropriate threshold values to allow for safe mining operations and does not address the issue of total strain. Surface movement monitoring data from a limited number of open pit mining operations in North and South America has been evaluated in terms of highwall strain, rock mass quality and inferred mechanism of instability. Threshold strain levels for key stages of highwall stability proposed from previous work has been reviewed and are endorsed based on evaluation of additional data. An empirical highwall strain criteria for the assessment of highwall stability performance is postulated based on relatively consistent trends in highwall strain data. L’évaluation du niveau de stabilité des hauts murs de carrières a traditionnellement été basée sur les taux de mouvements de surfaces. Bien que cette approche soit généralement acceptée à travers l’industrie, elle présente des défis pour la définition de seuils appropriés concernant la sécurité des opérations minières et n’adresse pas la notion de déformations totales. Des données de mouvements de surface provenant d’un nombre limité d’opérations minières à ciel ouvert d’Amérique du Nord et du Sud ont été évaluées en terme de déformation des hauts murs, de qualité de la masse rocheuse et des mécanismes inférés d’instabilité. Des seuils de déformation pour différentes phases clefs de stabilité de hauts murs ont été revus et sont endossés, basé sur l'évaluation de donnés additionnelles. Un critère de déformation empirique pour l’évaluation de la stabilité des hauts murs est postulé, basé sur des tendances relativement consistantes de données de déformations de hauts murs. Die Beurteilung der Stabilität von hohen Felsböschungen basiert traditionellerweise von Oberflächenbewegungen. Obwohl dieses Verfahren im Allgemeinen akzeptiert wird, stellt es jedoch gewisse Probleme für die Festlegung von Grenzwerten für die Sicherheit dar. Die totalen Dehnungen werden bei dieser Betrachtungsweise vernachlässigt. Eine beschränkte Anzahl von Oberflächenbewegungs Daten von Bergbauwerke in Nord- und Südamerika sind in Bezug auf die Dehnungen von hohen Felsböschungen, Felsqualität und davon abgeleiteten Bruchmechanismen untersucht worden. Grenzwerte für die Belastung von hohen Felsböschungen während den massgebenden Bauetappen aus bisherigen Projekten sind begutachtet und durch zusätzliche Untersuchungen bestätigt worden. Gestützt auf relativ konsitenten Trends, ist hier ein empirisches Verfahren der Dehnungen in hohen Felsböschungen zur Beurteilung der Stabilität vorgestellt.

Jan 1, 2003

By T. Nishimura, H. Kiyama, K. Wakimoto

Discussion on the load bearing capacity of ground and the stability of tunnel is presented. We derive a simplified solution of a circular lined-tunnel in an elastic ground. The solution results in a better understanding of characteristic curves. Use of DEM allows us to consider effects of possible yield of the overstressed zone around the tunnel and inherent discontinuity of ground on the curves. Diskussion auf der Last Tragfähigkeit Bodens und die Stabilität des Tunnels wird dargestellt. Wir leiten eine vereinfachte Lösung eines kreisförmigen Ausbautunnels in einem elastischen Boden ab. Die Lösung ergibt ein besseres Verständnis der Kennlinien. Um Gebrauch DEM erlaubt uns, zu betrachten Effekte des möglichen Ergebnisses der überbetonten Zone den Tunnel und zugehörige Unstimmigkeit des Bodens auf den Kurven. La discussion sur la portance de charge de la terre et de la stabilité du tunnel est présentée. Nous dérivons une solution simplifiée d'un revêtement-tunnel circulaire dans une terre élastique. La solution a comme conséquence une meilleure compréhension des courbes caractéristiques. L'utilisation de DEM nous permet de considérer des effets du rendement possible de la zone surchargée autour du tunnel et de la discontinuité inhérente de la terre sur les courbes.

Jan 1, 2003

By Gennady I. Gulyayev

A mathematical model of plastic deformation occurring in cold plug drawing of mother tubes with initial cross-sectional wall thickness variations (CSWTV) has been developed. The main provision of the model is that eccentricity em is of such value that projection of all forces acting upon the plug in the deformation zone along the axis perpendicular to the drawing axis equals to zero. Calculations have proven that with other conditions being equal increase in the die cone angle and the deformation cycle number reduces CSWTV. Theoretical findings were confirmed by practical results. Keywords: cold, drawing, plug, die cone, plastic deformation.

Jan 1, 2003

By Yasuo Ojima

A new copper continuous converting process was investigated to evaluate the possibility of its application in the commercial operation. The tests were performed both in the laboratory and in pilot plant scale. Bath smelting process with the use of the top submerged lance technology was applied in these tests. Furnace shape was modified to a lengthwise eylindrical one with a settling area. The furnace monitor was put in the settling area to check the furnace from inside, FeOx-Si02, FeOx-CaO and FeOx-CaO-Si02 based slag systems were used to check their efficiency, The optimum slag chemistry to have good metallurgical results was discussed and FeOx-CaO system with some Si02 content turned out to be preferable although it has not been practically used, In this pilot plant test feeding rate of I tIH of solid grain matte was charged consecutively for two weeks and continuous converting could be done successively. This process is expected to overcome the problems of existing processes and be easily applied in existing plants.

Jan 1, 2003

By William E. Roscoe

"Mineral exploration properties are those on which an economically viable mineral deposit has not yet been discovered. Such properties are bought, sold, optioned and joint ventured on the basis of their perceived potential for the existence and discovery of a viable mineral deposit. The intrinsic value of an exploration property is therefore based on the exploration potential. One measure of the exploration potential is the amount that can be justified to spend on exploration for a viable deposit.The appraised value method uses a cost approach to value exploration properties. It is based on the premise that an exploration property is worth the meaningful past exploration expenditures plus warranted future costs to test remaining exploration potential. Results of past exploration work are analyzed in order to retain only those past expenditures that are productive in terms of identifying remaining potential. Warranted future costs comprise a reasonable exploration budget to test that potential.INTRODUCTIONThe purpose of this paper is to describe a cost approach to the valuation of mineral exploration properties and to provide some valuation examples. The particular cost approach described is the Appraised Value Method, which is best applied to mineral properties at the exploration stage.At present there are no comprehensive regulations or guidelines in Canada which specify what approaches and methods to use for the valuation of mineral properties. In this paper, the Appraised Value Method described is one method that the writer considers to be accepted industry practice for mineral properties at the exploration stage.Mineral properties are valued for a number of reasons, including mergers and acquisitions, non arm's length transactions, pricing of initial public offering of stock, support for property agreements, litigation, expropriation, and insurance claims."

Jan 1, 2003

By A. Adu-Acheampong

Stope instability at Ashanti Goldfields Company Ltd. (AGC) is a major concern. Using information from field mapping, major discontinuity sets were defined, Rock Quality Designation (RQD) was determined. The stability of wedges in the stope walls was assessed using the commercially available computer program UNWEDGE(Rock Science, 1992). Analytical results indicate that the presence of graphite infilling in joints contributes to instability, while steeply dipping joints control wedge slabbing and wedge toppling in the hanging wall. Stable stope widths and dimensions were determined to range from8.1 to 30 meters (m).

Jan 1, 2003

By K. N. Karparov

The stress state on two slope profiles overlying an inclined surface with layer inclination of 50 and 150 are investigated. It is demonstrated that the induced stress state in an imbedded weak layer, exposed at the base of the slope, forms a zone of induced tensile vertical and horizontal stresses, which can lead to failure. The zone length depends on the slope angle and the angle of the inclined layers. L’état des contraintes sur deux profils en pente en superposition sur une surface inclinée avec une inclinaison de couche de 5o et 15o est étudié. L’étude présente démontre que l’état induit des contraintes dans une couche faible insérée, exposée au bas de la pente, forme une zone de contraintes de traction induites horizontales et verticales, qui peut amener à la rupture. La longueur de la zone dépend de l’angle de la pente et l’angle des couches inclinées. Die Druckvorkommnisse zweier Hangprofile auf einer schrägen Fläche mit einer Schichtneigung von 5º und 15º wurden untersucht. Es zeigte sich, dass die induzierten Druckvorkommnisse in einer eingebetteten schwachen Schicht, die am Hangfuße offen liegt, einen Gürtel induzierter vertikaler und horizontaler Zugkräfte bildet, die zum Zusammenbruch führen können. Die Gürtellänge ist von der Neigung des Hanges und der Neigung der schrägen Schichten abhängig.

Jan 1, 2003

By James Pile

The San Juan Coal Mine, located near Farmington, New Mexico, supplies the San Juan Generating Station with more than 6 million tons of coal annually. To replace dwindling surface mine production, San Juan installed a longwall in 2002. The roof rock in much of the underground reserve consists of interbedded coals, carbonaceous shales, and mudstones. Roof support consists of fully-grouted roof bolts, both tensioned and non-tensioned, supplemented by modified cable trusses. Short-encapsulation pull tests conducted by San Juan's geotechnical engineering department showed that some of the immediate roof layers provided variable bolt anchorage. To ensure that the roof bolts were obtaining the necessary anchorage, additional tests were conducted in a variety of locations. The results have been used to determine the optimum support design for different areas of the mine. Another series of tests evaluated the performance of several bolt and hole diameter combinations. The experience at San Juan Mine shows that short-encapsulation pull tests can provide the information necessary to improve ground control in variable roof conditions. It also illustrates how a pro¬active geotechnical engineering program can be an essential component of a state of the art underground coal mine.

Jan 1, 2003

By D Craw, C E. Martin, C Smith, C Rufaut

Wangaloa Coal Mine opened in 1945, and by the time of its closure in 1989, had produced 750 000 tonnes of coal and disturbed an area of 75 ha. The original mining licence required land rehabilitation to exotic forestry, however the current owner, Solid Energy, has worked with Crown Minerals and local councils to write a new rehabilitation objective. The site is now being stabilised and replanted with native species, and may be available for public use before the coal mining licence expires in 2007. Site discharge permits expire in 2017, and by that time, it is anticipated that discharge water chemistry will be similar to background levels. MWH are currently contracted for management of the mine rehabilitation project. The Kaitangata coal unit mined at Wangaloa is sulfurous lignite with associated pyrite. Kaitangata coal contains 3.2 wt per cent sulfur, which is higher than most New Zealand coals. Initial analyses at Wangaloa indicate low pH (2.56.2) values in soil, groundwater and surface waters as a result of acid rock drainage (ARD) processes, leading to increased metal mobility and challenging conditions for vegetation. Pilot studies indicate pinus radiata needles contain up to 67 mg/kg boron, and elevated As, Cu and Zn concentrations in surface waters. The main lake at the site has a pH of approximately 4.9, despite lime dosage in 2002. There is a real need for a complete geochemical model of the Wangaloa coal mine. Such a model could be applied to similar restoration projects, and would assist by pinpointing geochemical processes and toxic metal relationships most harmful to the receiving environments. Using this model, rehabilitation in the future will be targeted and more efficient. This project is part of a larger scheme to characterise and model the Wangaloa mine site restoration, including waters, soil, vegetation, geology and invertebrates.

Jan 1, 2003

By Wang Xuguang, Zhang Xiaozhi, Li Guozhong, Xiong Daiyu

The emulsion explosive is a new kind of water-based industrial explosives that was developed at the end of 1960s. In the 1970s, BGRIMM invented EL-series emulsion explosive that created a new era of water-based industrial explosives technology and products in China. From single type to varieties, the perfect BGRIMM emulsion explosives technology has been formed, which consists of 9 series, over 30 types explosives and related production equipments and processes such as cap-sensitive rock emulsion explosive, opencast emulsion explosive, coal permitted emulsion explosives, low-temperature-resistant emulsion explosive, high-temperature-resistant emulsion explosive, high power emulsion explosive, bulk emulsion explosive for loading truck and powder emulsion explosive. From the early 1990s, BGRIMM successfully developed opencast emulsion explosives and the computer controlled continuous production line of small-diameter cap-sensitive emulsion explosive which raised emulsion explosive production technology of our country to a new lever. With the successful development of powder emulsion explosive and related computer controlled continuous production line, on-site mixed emulsion explosive and loading truck as well, the category of industrial explosives is getting more complete and reasonable. This paper pres ents the history, achievement and development of BGRIMM emulsion explosive technology, also forecasts the future of linked technology.

Jan 1, 2003

By T. Skinner, M. Sahebkar

"In recent years, the mining industry has been inundated with new technologies and software systems to aid in productivity improvement. Accompanying this increased level of technology and computer systems has been the exponential growth in data sources and sinks for all aspects of a mining operation. This rapid growth in data and technology has evolved through vendor “push” approaches and user “pull” scenarios, the result of which has been that currently, no standards exist defining how data from new technology should be accessed and transferred from surface mining equipment and systems. Consequently, many incremental benefits of the systems have not been realized. This paper will present a discussion of this important issue and introduce a new committee formed to address standards to assist the industry in making effective use of current and future technology. Potential benefits accruing from the development of these standards will be illustrated through the use of a case study at Fording Coal Limited. IntroductionThe mining industry is currently faced with a rapid evolution in the computing-based systems capabilities of mobile production equipment. At the same time, there is a trend toward the introduction of even larger machines, with novel designs or incorporation of new technologies within existing designs. Computing and control technology will be required to operate and acquire knowledge about equipment operation, utilization, and performance. Such knowledge has the potential to lead to enhanced equipment design, more appropriate equipment selection, and optimized equipment performance. The equipment systems will be required to be integrated with mine production monitoring systems, maintenance management software, and a wealth of other information systems to provide a complete understanding of the effects of various factors such as maintenance, equipment design and production on economics (Roman and Daneshmend, 2001). This will lead to a better understanding and implementation of the opportunities to enhance the performance of the mine through interaction of the mine operations."

Jan 1, 2003

By C Noble, J Webster-Brown

A survey of selected West Coast Streams was undertaken in Summer 2001, Summer 2002 and Winter 2002 to establish the degree of arsenic (As) contamination in waters and sediments downstream of old coal and gold mine workings on the West Coast. Of the catchments studied, Soldiers/Ford Creek and Rapid Stream showed the most significant elevated As concentrations, predominantly in dissolved form, and evidence of AMD or ARD contamination (high sulfate concentrations and/or acidity). The rate and processes of removal of dissolved arsenic from the water column (attenuation) have been studied in these catchments. The Rapid Stream and Soldiers/Ford Creek catchments are directly affected by adit drainage from the Sullivan and Blackball coal mines respectively. Both catchments have high As concentrations in the sediments, with up to 770 mg/kg in Soldiers Creek and 490 mg/kg in Rapid Stream. Dissolved As concentrations are significantly elevated in the neutral pH waters of Soldiers Creek; typically as high as 100 - 200 ¦g/kg, up to 500 m downstream of the main adit discharge (800 ¦g/kg As). Adit inflows to Rapid Stream were acidic and contained 20 - 30 ¦g/kg dissolved As, with relatively high concentrations of arsenic in the stream water in winter (up to 18 ¦g/kg), but not in summer. Analysis of concentration trends and As:SO4 ratios downstream of these obvious As sources confirmed that dissolved As had been actively removed from the water column, but varied seasonally with greater removal evident in summer. Adsorption of arsenic onto iron oxide in the stream sediments is the most likely mechanism of removal. The Snowy River catchment, on the other hand, has relatively high As concentrations in both the sediments and the water column, but there was little evidence of a distinct AMD or ARD input from the Blackwater gold mining area. Preliminary investigation suggests that dilution rather than attenuation is responsible for decreasing As concentrations downstream.

Jan 1, 2003