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By Nobuyuki Higashiyama, Ikuo Yonezu

"Hydrogen-absorbing alloys containing rare-earth elements are used in high capacity nickel-metal hydride secondary batteries,' hydrogen storage systems for portable fuel cells, and refrigeration systems. New hydrogen-absorbing alloys containing rare-earth elements have also been developed and introduced into these applications. High performance in nickel-metal hydride secondary batteries is strongly demanded because of the remarkable advancements in portable electric appliances. A large hydrogen absorption capacity, high electrochemical reactivity and superior corrosion resistance in an alkaline solution are required for hydrogen-absorbing alloys used in nickel-metal hydride batteries. The aim of this investigation is to improve the performance of conventional LaNi5 type hydrogen-absorbing alloys. For example, Mm(Ni-Co-Al-Mn)„ type hydrogen-absorbing alloys with various non-stoichiometric compositions were developed. In addition, a new process of rapid quenching process was applied for preparing these hydrogen-absorbing alloys in order to improve their performance.IntroductionRecently, the trend in electronic appliances toward portability has increased the demand for high capacity of secondary batteries as power sources. Since nickel-metal hydride batteries were first commercialized in 1990 in Japan, they have become increasingly popular as power sources for cellular phones, portable computers, electric shavers, and other, products.The performance of a nickel-metal hydride battery, such as its discharge capacity, high rate capability, and charge-discharge cycle life, strongly depends on the characteristics of the hydrogen-absorbing alloy negative electrode. Many types of hydrogen-absorbing alloys have been developed so far. For a hydrogen absorbing alloy to be used as the negative electrode material, (1) it must allow a large amount of hydrogen to be absorbed and desorbed in an alkaline solution, (2) its reaction rate should be high, and. (3) it must have long term durability under repeated charge-discharge cycling. However, LaNi5, a typical rare earth-nickel type alloy, shows significant capacity deterioration during repeated charge-discharge cycling. Therefore the first step in its development was to obtain sufficient corrosion resistance of the LaNi5 alloy for its use as an electrode material. A partial replacement of nickel with cobalt and a substitution of the lanthanum- content with misch metal (Mm), a mixture of rare earth elements such as lanthanum, cerium, praseodymium and neodymium, were very useful in improving the charge-discharge cycle life. However, the discharge capacity of the alloy was still not sufficient for a practical battery. A study of the effect of the partial substitution of aluminum and manganese showed that the best alloy composition was Mm(Ni-Co-Al-Mn)x, as follows.The stoichiometry x of Mm(Ni-Co-Al-Mn)x largely affects the discharge capacity and cycle life. Theose alloys with non-stoichiometric alloys with the compositions of [Mm(Ni-Co-AMn)x: 4.7<x<4.8] have a large capacity and a long cycle life. Nogami' et al. reported that 'a non-stoichiometric alloy with a Mm(Ni-Co-Al-Mn)x (x=4.76) composition showed approximately 10% higher discharge capacity than the stoichiometric alloy (x=5) [1] and greater influence of x on the electrochemical properties of multi-component AB„ type hydrogen-absorbing alloys for batteries."

Jan 1, 2000

In the course of the last twenty eight years the copper lodes of New Caledonia have been periodically worked or abandoned, until quite recently, probably attracted by the higher price of the metal, British capital has again been induced to embark upon the further development of several copper properties, which at present give reasonable promise of becoming regular producers. Owing to its proximity to Australia (only a three day&apos;s journey by mail steamer from Sydney) New Caledonia becomes of additional interest to Australian commerce in general, and it is to be hoped that the French Government may see their way before long to make the best of this natural position, to the mutual benefit of both countries concerned.Op till now all copper ores and concentrates which have been shipped from New Caledonia, were treated in Australian smelting works furthermore, Australian mine managers and miners have from time to time been connected with New Caledonian mining ventures, but, unfortunately, it must be said that nearly everyone of them returned to Australia thoroughly disgusted with his experience over there. Even to the casual observer, it is not so very difficult to find a proper explanation for these shortcomings in the peculiar economic conditions of the &apos;French colony, as many of the objections which have hitherto existed in connection with mining operations, were the direct consequences of a system of colonisation which could not possibly have been productive of better results.

Jan 1, 1901

Extending an organization?s knowledge base throughout the entire enterprise can improve operations. Until recently, though, field operations were often left out of the information loop, as extending high-bandwidth communications into harsh environments often proved impossible due to thermal extremes, physical hazards and caustic chemicals. However, advances in the design and manufacture of rugged fiberoptic cables have now enabled the successful installation of 10-gigabit transmission links to places such as mining operations. The experience of Consol Energy exemplifies how plant managers can successfully enlist ruggedized tight buffered cables to help carry the efficiency of ERP communications into even the most challenging work environments. ?As part of our ERP implementation, we extended our corporate network underground into our mines using fi beroptic cable,? said Tom Prokop, manager-site support for Consol Energy. ?We?ve actually had rooffalls bury the cable between rocks and still did not lose data communications. Our maintenance personnel are now able to access our ERP system while underground at locations that can be up to 32 km (20 miles) away from their desks or the warehouse. Access to the corporate network allows them to order parts, look at electronic schematics, access monitoring data, no matter where they are in the mine. With a few hundred workers below ground, this immediate access translates into a time-savings that adds up in a hurry.?

Jan 1, 2009

By C Johnstone

Project management is not a task to be undertaken lightly. Mining projects generally present even more challenges due to ChinaÆs remoteness and complexity. Having experiences in project management in the West is certainly an asset, but China can present the uninitiated with any number of headaches. To undertake a project there can have many problems that are unique to China. For the last 15 years, China has seen an increasing number of foreign capital investment projects in the mining industry. Practices involved in mining project development have experienced/are experiencing an evolution. Since 1996, Sino Gold Mining Ltd has delivered three mines in China, ie Jianchaling Gold Mine, Jinfeng Gold Mine and White Mountain Gold Mine. Through the work, Sino Gold has established a solid knowledge base and a capable and skilful workforce in effectively undertaking mining projects in China. This paper is concerned with the experiences accumulated so far by Sino Gold in project management in China. An overall review is conducted regarding the reform of the mining project development in China. Opportunities and challenges are highlighted within the political, economic and culture context. Brief summaries of the development of the three gold mines are presented.

Jan 1, 2009

By M. Rahmanpour

"Mine planning is a multidisciplinary procedure that aims to guarantee the profitability of a mining operation in changing and uncertain conditions. Mine plans are normally classified as long-term, intermediate-term, and short-term plans, and many factors affect the preciseness of these plans and cause deviations in reaching the objectives. Commodity price is the heart of mine planning, but it has a changing and uncertain nature. Therefore, the determination of mine plans in the presence of uncertain mineral price is a challenge. A robust mine plan reduces the risk of early mine closure. A procedure is presented to determine the value at risk (VaR) in any possible mine planning alternative. VaR is considered together with downside risk and upside potential in order to select the most profitable and least risky plan. The model is tested on a small iron ore deposit. IntroductionMining projects are normally evaluated with the objective of maximizing economic value, as measured by the net present value (NPV). The aim of mine planning is to develop a yearly extraction plan that guides the mining operation to the highest NPV (Dagdelen, 2007; Yarmuch and Ortiz, 2011). This plan considers the technical constraints such as blending requirements, block sequencing, and pit slope (Caccetta and Hill 2003). Thus, the mine plan affects the economics and the payback period of mining operations.Mine planning is a procedure based on which the profitability of the mining operation is guaranteed in changing and uncertain conditions (McCarter, 1992). However, conventional mine planning ignores the volatility and uncertainty of future commodity prices and does not allow for managerial flexibility. It is common practice to assume a deterministic and constant commodity price through the mine life. The problem with this approach is that the commodity price is the heart of the mine planning procedure and governs the profitability and feasibility of the operation; thus ignoring price volatility will result in a sub-optimal mine plan."

Jan 1, 2016

By Tom C. Palangio

The mining industry has come to rely on imaging devices to monitor and record all kinds of activities. We use them to measure, improve the process, ensure security, increase production and automate machinery. Cameras can be installed in locations most people wouldn?t want to live and be our ?eyes? to record the events at that location. This paper discusses digital imaging, the equipment, methods, techniques and information that can be learned from digital devices used in mining operations. The guy who said ?a picture is worth a thousand words? probably understated it. Images are the perfect way to document conditions before, after and even during mining activities. Today?s wide choice of cameras, camcorders and other digital devices allow us to record most activities and events. The technology is advancing at a high rate. Digital cameras and camcorders are marvels of technology with high resolution optics, compact size, automatic time and date stamp, great battery life, shutters to freeze motion and computers to auto focus and eliminate jitter (image stabilization). Add to this the economical price and ease of use and everyone in this industry should be aware of the possibilities.

Oct 1, 2010

By Larry S. Diaz

The paper considers the selection of control instrumentation for a modern flotation plant, as well as the best interpretation and most effective use of the process data obtained. Process control computer availability is considered from the outset. A general philosophy of control is proposed which leads toward a system that is its own reliability monitor. The bulk of the problems are in grinding and classification. Alternative control methods are described that use particle size measuring devices. Flotation controls, based to a large extent upon on-stream X-ray analysis, are reviewed in detail. Reagent control methods are also examined. Methods to analyze the data obtained from the various measurement devices are introduced. These methods would enable an estimate of the validity of the data and require some redundant information. Another objective of these methods is the protection of operating equipment from possible control malfunctions. Although the discussion generally considers some degree of computer usage, this paper attempts to describe instrumentation and data analysis methods that enable control with or without the process control computer.

Jan 1, 1972

By Reda M. Bakeer

"Measurements obtained during load testing of two steel H-piles driven at a site in Northeastern Mississippi are discussed. The general site conditions, equipment used, testing procedures and results of the pile load tests are presented. Both piles were tested in compression and one of the piles was subsequently tested in tension. The piles were instrumented with strain gauges and extensometers to measure the mobilized soil resistance and pile movement. Three different “zero strain” conditions were used to determine the mobilized soil resistance and residual loads due to driving or a load cycle. It was concluded that the effect of residual loads on driven piles could be significant. Driving residual loads influenced the magnitude and distribution of the load transfer curves more than those due to a load cycle. Results of the tension test were impacted by the residual loads from the previous compression test performed on the same pile.INTRODUCTIONSeveral factors affect the performance of a deep foundation system including the subsoil conditions, loading settings, pile type and installation method. Residual stresses develop in piles particularly due to pile driving, but they are typically not accounted for in the analysis (Fellenius 2002). Siegel and McGillivray (2009) presented an assessment of residual loads measured during load testing of instrumented auger-cast-in-place (ACIP) piles. The magnitude and distribution of residual stresses along the pile shaft and toe depend on the pile installation method, previous load cycles and time effects. Poulos (1987) reported that residual load due to driving at the pile toe is independent of pile driving equipment and may significantly affect the results of a pile load test. Hunter and Davisson (1969) reported results of pile load tests performed in compression on fully instrumented piles driven in cohesionless soils along with a discussion of the effects of residual loads. Tension loads of about 445 kN (100 kips) were measured at the pile toe after driving. Unloading residual compression load at the toe was detected as “apparent” tension since the instrumentation was zeroed prior to the test. The researchers suggested a graphical approach to obtain the “corrected” load distribution curves considering that residual load will dissipate following the tension test. Holloway et al. (1975) conducted a study on the effect of residual stresses due to pile driving and developed a computer software that accounts for residual loads. Briaud and Tucker (1984) suggested a method to account for residual loads based on the results of 33 pile load tests performed in mostly cohesionless soils."

Jan 1, 2017

By Pierre Rocque

The Red Lake Mine is located approximately 600 km northwest of Thunder Bay. This 545 tpd (600 tons/day) underground narrow vein gold operation is set to produce in excess of 14.8 tonnes (475,000 ounces) in 2001 at a cash operating cost below 75 U$/oz. The high-grade nature of this deposit (>55 g/t or >1.6 opt) coupled with its complex geological environment and relatively deep location dictated the choice of a very selective primary mining method, Mechanized Overhand Cut and Fill. In addition to geological challenges, mine design issues such as material handling, ground stability and requirements for yieldable ground support are also discussed in this paper.

Oct 1, 2001

By S Colak, M Tunc, C Celik, M. M. Kocakerim

The most important parameters affecting the solubility of ulexite (sodium calcium borate) in H2SO4 were found to be reaction temperature and solid:liquid ratio, in that order. Dissolution increased with increase in temperature and stirring speed and with decrease in solid:liquid ratio, particle size and acid concentration, the last effect as a result of decreased precipitation of CaSO4 on unreacted particles. Optimum conditions, in which around 99.5% of the ulexite could be dissolved, were a reaction temperature of 60 degrees C, a solid:liquid ratio of 1:8 g/ml, an acid concentration of 8 mol/l, particle size smaller than 425 micrometres, a stirring speed of 52.33/s, a reaction time of 1 800 s, a calcining time of 3 600 s and a calcining temperature of 170 degrees C. These conditions, determined by the Taguchi method, are reproducible in a commercial production environment

Jun 21, 1905

By M. R. Tek, L. K. Thomas, D. L. Katz

Threshold displacement pressures are needed to determine how much overpressure can be used in storing natural gas. An experimental technique for determining threshold pressures by displacing water with gas from samples saturated with water is presented. Threshold pressures for eight low permeability samples were measured. Threshold pressure data obtained in this work, plus data on higher permeability samples reported in the literature, are correlated with porosity, permeability, surface tension and formation resistivity factor. Mercury injection pressures also were measured and correlated with air-water threshold pressures. Threshold pressures were found to be independent of time. An aerial photograph of gas emerging from the top of a core shortly alter its threshold pressure has been exceeded shows that the gas bubbles are uniformly distributed across the face of the core. Channeling will occur, however, when an increased gas phase permeability is reached, A porous medium can be re resealed alter its threshold pressure has been reached, provided it has not been desaturated below a fixed saturation. Its new threshold pressure will be lower than when the sample is 100 percent saturated with water. INTRODUCTION The degree of overpressure in excess of the discovery pressure that a gas storage reservoir can withstand is determined by the ability of its caprock to contain gas, providing the pressure does not exceed the structural limit of the reservoir. The retention of gas in a reservoir by a caprock saturated with water is a result of the capillary forces acting at the gas water interface. Without the presence of water in a caprock, gas would leak out of the reservoir at a rate determined by the permeability of the caprock to gas. The ability of a caprock to contain gas is expressed in terms of its threshold displacement pressure, which is defined as the minimum pressure needed to initiate the displacement of a wetting phase by a nonwetting phase from a porous medium 100 percent saturated with the wetting phase. The gas industry must be able to predict how much "overpressure" a gas reservoir can withstand before leakage occurs by gas displacing water from caprock overlying the reservoir. This is of economic importance since the storage capacity of a gas reservoir is proportional to its pressure. The discovery pressure for most reservoirs is found between the upper and lower limits1 shown in Fig. 1. Discovery pressures in excess of their hydraulic pressure gradient are attributed to the compaction of an isolated shale formation by the overburden.2.3 The lower limit of 0.433 psi/ft corresponds to the weight of the overburden, the gradient of the rock itself. Somewhere between

Jan 1, 1969

Discussion of the paper of R. J. COLONY, presented at the New York Meeting, February, 1921, and issued With MINING AND METALLURGY No. 169, January, 1921. R. J. COLONY (author&apos;s reply to discussion).-The work of Sosman and Merwin on the system lime-ferric oxide, mentioned by Mr. Rankin, was not overlooked. When studying portland cements and portland-cement clinkers petrographically, however, the lime-iron compound was difficult to correlate with the very definite dicalcium ferrite described by those investigators, which possesses such well-defined optical properties. In portland cements, the calcium ferrite (or ferrate?) is an indefinite, fuzzy, and generally amorphous, or apparently amorphous substance that is distributed interstitially with respect to the other grains, from which it was very difficult to derive any satisfactory results. For this reason, the writer, tentatively, chose to regard it as related to the aluminate, and assigned to it the composition 3CaO.Fe203, which may be incorrect, however, as Mr. Rankin suggests.

Jan 8, 1921

By Frank Armstrong

ALL the mining machinery of the Penn Iron Mining Co. has been operated by electric power for several years and when another shovel for stockpile loading was required the advantages of an electric shovel were naturally considered. After considerable study, serious objections suggested themselves the use of a shovel operated directly by electrical apparatus by reason of the complicated control, severe service on the motors FIG. 1.-ELECTRO-HYDRAULIC SHOVEL FIG:. 2-THE SHOVEL AS IT WAS OPERATED CINDER CONSTRUCTION. THE FIRST YEAR. and the heavy surges of current required from the line. It was finally decided to construct an electro-hydraulic shovel using water under pressure to perform all the necessary operations except that of propelling, for which a separate motor was best suited. A car body with boom, dipper handle and dipper of late design, but without any of the steam machinery, was purchased. A motor-driven centrifugal pump, a pressure tank, an air tank, a small air compressor and water cylinders with plungers, pistons and valves, were installed in place of the; steam equipment. Fig. 1 shows this shovel under construction and Fig. 2 shows it as it was operated during the first year, the summer of 1914. The large tank at the back of the car, in Fig. 1, carried air under

Jan 2, 1916

By John P. Harmon

Vehicles traveling on untreated dirt and gravel roads at open-pit mines disseminate high concentrations of dust (fig. 1). Excessive dust creates safety hazards by reducing visibility and may endanger the health of the men who breathe it. If the dust contains free silica, it can cause silicosis. In addition, maintenance costs of mechanical equipment are increased if equipment is operated in extremely dusty places. Dust on haulage roads in hot, arid country can be controlled if the surface of the road is sprinkled frequently and adequately with water. Often, when roads are sprinkled with water to control the dust, hazards are caused through reduced traction and skidding because of the mud that is formed on the surface of the road. Reducing the amount of water used will help to reduce the hazard of skidding.

Jan 1, 1957

By Peter J. Nicholson

Since the reintroduction of soil mixing to the United States over 10 years ago, the work installed by soil mixing technology has grown dramatically. From an annual turnover of less than ten million dollars per year the volume of soil mixing put in place has grown to an estimated $40 million per year in the year 2000. The majority of work done to date has involved walls, either for excavation support, permanent retaining structures or hydraulic cut-off walls. The other major use for soil mixing has been for mass stabilization of soils whether for isolation of contaminants or for retaining structures. This paper will discuss the uses of and costs of typical soil mix structures. BACKGROUND Soil mixing is defined as the in-situ combining of reagents, typically cement, with native soils, the purpose being to modify or improve the ground. This history of soil mixing covers only the use of cement slurry, aggregated with soil in-situ by mechanical mixing methods only. Soil mixing by use of high-pressure hydraulic means, also known as Jet Grouting, will not be discussed. In addition this will not cover ex-situ (above ground) mixing, or mixing dry reagents with soil. Only mixing applications for building, civil and heavy construction applications will be discussed, with only passing reference made to uses of soil mixing for environmental remediation work.

Jan 1, 2001

Approximation of Surface Area of Fines in Blast Induced Fragmentation The surface area of fragmentation, especially in the finer size fractions, is a useful property to characterise the mechanisms of rock breakage. In the past, researchers have made assumptions with regard to the shape of fragments in order to estimate surface area, such as that all fragments are the same shape or all fragments are spheres. Often these assumptions were developed with inappropriate measures and returned considerable variability and error for the calculation of surface area. This paper reports a model to estimate fragmentation surface area from sieve sized raw data and a density measurement, with experimental validation down to a size fraction of -45 + 38 ?m in a range of rock types. After characterisation of particle shape, a range of fragment shapes was found to be in each size fraction. Nevertheless, in the ?2 sieve series the average fragment mass, volume and the size fraction standard deviations could be predicted reasonably accurately. Ellipsoid geometry was used to describe particle shape. Using these parameters and the number of fragments (also predicted) in each sieve size the individual surface area of each fragment was simulated.

Sep 13, 2010

By Darrell L. Beddard

Pile driving started October 29, 1993 and was completed on January 27, 1994. Field work included driving piling from ground surface at one site and at or near proposed footing elevations for the remainder. Piles were driven to specified tip elevations or the elevations directed by the Project Manager. In an attempt to address what installation technique(s) performed the best, several methods were used, including varied predrilled depths, open ended piles, closed ended piles, and the use of both impact and vibratory hammers. Piles were driven closed ended where possible to study the feasibility of this option to reduce construction costs associated with pile cleanout. Piles were driven to different depths to measure capacity variations. The 24-inch (610 mm) diameter piling were driven in one piece while the 42-inch (1.07 m) diameter piling was driven in two segments. A total of 79 piles were driven for the four sites, 74 of the 24-inch (610 mm) diameter and 5 of the 42-inch (1.07 m) diameter. Various hammers were used to determine which hammers provided viable solutions to the potential problems anticipated in the design phase. Hammer selection was based on the driveability studies. Equipment included a 175 ton (1.56 MN) crane, support crane for pile stabilization, crane mounted auger drill, offshore leads, Delmag D30-32, D46-32, and D62-22 diesel hammers, an HPSI 2005 single acting hydraulic hammer, a Foster IHC S-90 double acting hydraulic hammer and a Kencho VM2-25000AII vibratory hammer with the weights set to produce 17,500 pound-inch (1.98 kN-m) of eccentric moment.

Jan 1, 1996

By Nikolaus Schneider

"Abstract: The combination of failure in joints of diaphragm walls and their exposure to water pressure may have far reaching effects ranging from water leakage to the risk of catastrophic loss of stability for the retaining wall and civil structures behind it. Investigations of imperfect joints in diaphragm walls have led to the development and testing of a quality tool to monitor the joint integrity of diaphragm walls during construction. By applying independent mechanical sensors (“joint inspector”) to the steel frame of hydraulic or mechanical grabs, it is now possible to record the surface conditions of exposed primary joints during the construction of secondary panels. This allows for the implementation of corrective action during the construction process should joint quality not indicate a watertight connection to the adjacent panel. The joint inspector, used for different types of stop ends, was tested on a full scale test field at several construction sites. The implementation of this new quality tool drives a new quality standard for deep excavations in inner city areas.General introduction to diaphragm wallsDiaphragm walls are reinforced concrete elements constructed using bentonite slurry to temporarily support an open trench in the ground. They are used in two main fields of application in civil construction, as foundation elements for vertical and horizontal loads (barrettes) and as retaining walls for excavation pits.Particularly for deep excavation pits in inner city areas, diaphragm walls are used as temporary or permanent walls of retaining walls. Alternative retaining wall systems would be secant pile walls, sheet piles or soldier piles, but these have disadvantages in structural strength when compared to diaphragm walls. If the vertical load of existing buildings next to the excavation pit has to be accommodated, the most practical solution can be found using diaphragm walls supported by prestressed anchors, steel struts or slabs."

Jan 1, 2014

Construction of the Boddington Mine 130 km (81 miles) southeast of Perth, is about 89 percent complete. When the $2.9-billion development is finished, it will be the largest gold mine in Australia, producing 31 t/a (1 million oz/year), according to project majority owner Newmont Mining. Newmont?s acting regional group executive for Asia Pacific, Philip Stephenson, told a gold conference in Australia that the project would be ?the biggest thing for Newmont this year.? The project has been in the works for more than 10 years, but because of a three-sided ownership and fluctuating gold prices, it struggled to get started. However, Newmont is set to become the full owner of the project and is moving ahead on the low-grade project. ?We are targeting annual production of 31 t/a (1 million oz/year) for each of Boddington?s first five years. When it is in full production, Boddington will be the largest gold mine in Australia,? Stephenson said. ?The mine?s costs applicable to sales will be around US$9.64/g (US$300/oz) and that puts Boddington into the bottom quartile of the global cost curve. ?Strategically for Newmont, Boddington coming on-line will improve Newmont?s overall global geopolitical risk profile as it delivers greater exposure to an AAA-rated country.? Boddington has a projected mine life of 20 plus years. It has current total reserves of 622 t (20 million oz) and rising. Stephenson said Boddington has the largest reserve base of all gold projects in production or those that are about to go into production in A-rated countries or better. And it will be an important asset for many years to come. Newmont will acquire the remaining 33 percent share held by AngloGold Ashanti in a deal that should be concluded in the next two months. Australian miner Newcrest Mining Ltd. had exited the joint venture several years ago. Newmont had come into the project through the take-over of then Australia?s leading gold miner Normandy Mining, while AngloGold Ashanti gained entry through

Jan 1, 2009

By John A. Owsiany

The effect of longwall mining on streams and shallow aquifers has been the subject of numerous research studies for more than twenty years. As a result of these studies, it has become common to consider an overburden thickness of 400 feet as the lower limit at which longwall mining methods may be used with little or no effect on hydrologic systems. This paper presents the results of a study documenting the response of a large high order stream to shallow cover undermining by longwall methods in the northern Appalachian coalfield. The field site is located in a narrow stream valley where the overburden, composed primarily of limestone and sandstone units interbedded with shales and siltstones, ranges in thickness from 340 to 285 feet above the main bench of the Pittsburgh coal seam. Streamflow monitoring and monitor well measurements indicate that no significant loss zones or water table lowering resulted from undermining the stream or the adjacent valley bottom area. Additionally, hydrographs for shallow near-stream wells exhibit fluctuations related to natural seasonal variations, which are nearly identical to those observed in a non-undermined control well in the same watershed. Environmental factors affecting streamflow were monitored through the use of a control stream in an adjacent non-undermined watershed to differentiate between natural and mining induced changes in flow.

Jan 1, 2001