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By John C. Cook

In reasonably dry rock, long-wave radar can theoretically explore to distances approaching 75 meters (250 ft). High-resolution radar reflections have already been demonstrated through 13 m of hard limestone, through 9 to 18 m of coal in place and through 225 m of rock salt, using only low-power experimental radar equipment. Radar reflections have been received through the rock from rough pillar walls, from faults, and from a slim, uncased, vertical drill hole. In three years of intermittent experimentation, the feasibility of rapid radar exploration of large volumes of rock, with portable equipment, in deep, wet workings has been demonstrated. With future, improved equipment the theoretical working range, of the order of 75m, is expected to be attained in most hard rocks. THE TECHNIQUE Fig. 1 illustrates an early "monocycle" radar system (1) set up in a coal mine. This radar equipment is entirely different from that employed for detecting distant objects through the atmosphere. However, the basic principle is the same: a pulse of electromagnetic energy is radiated by the transmitter, a portion is reflected by some "target" object embedded in the surrounding medium and some of this energy is collected by the receiving antenna. In the receiver, the pulse is amplified, is "stretched out in time" by a sampling process, and is displayed on the screen of a cathode-ray oscilloscope. It may also be recorded on paper or magnetic tape. Fig. 2 illustrates a

Jan 1, 1997

By R. V. Ramani, R. Srikanth

A three-part study was conducted to relate the dust generation propensity of a coal sample, defined here as the dust generation rate (grams of dust generated per tonne of coal broken), to its characteristics, in order to rank coal seams according to their respirable dust generation potential. In this paper, the results of a single breakage study on a variety of coal samples encompassing all coal ranks, and samples from operating mines are discussed. Further, where data are available, the primary dust generation rates of coal samples collected from underground coal mines are compared with the in-mine dust generation rates. The results of this analysis are then used to apply the results of this study to longwall face ventilation design. Vitrinite reflectance, and level of organic metamorphism are highly correlated with primary respirable dust generation rates of bituminous coal samples. The dust generation rates in underground coal mines are an order of magnitude higher than the primary dust generation rates in the laboratory. Depending on the type of coal, production rates, and dust control procedures, the air quantity required for airborne dust control can vary significantly. The air quantities on some high production longwalls are approaching the limits beyond which it may not be possible to reduce ambient ARD concentrations to less than 2 mg/m3 by dilution ventilation alone. In these cases, the miner's exposure should be controlled through the use of personal protective de- vices and administrative practices.

Jan 1, 1997

By Valcana Stoyanova

The distribution pattern, abundance variations and types of polymetallic nodules and associated megabenthic communities in area covers more than 60 000 km2 laid out in the eastern Clarion-Clipperton Zone (CCZ) is presented. Our observations are based on data from 158 boxcore stations collected during the cruise of the Interoceanmetal (IOM) in 2004 on board of RV Yuzhmorgeologiya. Although those polymetallic nodules for two decades been subject to prospecting and exploration studies carried out by IOM, the knowledge of megabenthic communities and their distribution pattern within nodule field was extremely limited. With purpose to evaluate the relationship between polymetallic nodules and associated benthic megafauna, an comparison analyze was carried out in respect to their composition, types, abundance across the studied area owing into account the local particular feature of bottom topography. It is suggested that the nodule-bearing seafloor supported more diverse fauna (higher number of morphotypes) than the nodule-free areas. Moreover, based on correlation between types of nodules and associated faunal morphotypes frequency the apparent relationship is considered. The most abundant megafaunal taxa (between 68 ? 92%) is essentially associated with the occurrence of the diagenetically growth nodules type (D-type and its D1-subtype); the role of the H and HD nodule-types was variable. In respect to the bottom topography, the highest diversity in the structure of megafaunal communities was recorded in the gently undulating plains and on the horst slopes, thus the highest nodule abundance occur on the topographic slopes.

Jan 1, 2008

By W. Blake, J. Mahaut, W. Hustrulid

Division II at Kamoto mine in Kolwezi, Zaire represents a transition zone between Divisions I and III where transverse and longitudinal cut-and-fill rooms were being mined. Because this transition zone had been geologically depicted as being badly faulted the mining in this division had been deferred to a future time. However, to increase production and to reduce mining costs by carrying out the mining of the 3 divisions simultaneously, it was decided to mine Division II. The mining research group of Gecamines was given the task of designing a mining geometry then testing this design in a full scale test. Based on an evaluation of the faulting and fracturing of the 2 parallel orebodies and on an extensive in situ testing program preliminary mathematical analyses were used to develop and evaluate room and pillar designs in the 35°-65° dipping bedded formations. Based on these analyses and the constraints of having to fit the design of Division II to grade into Divisions I and III in a logical manner, a mining geometry for Division II evolved. To test this design an instrumented room was excavated in the most critical area. The results of this full scale testing showed that the behavior of the roof and wall rocks were as had been predicted by finite element computer model studies which incorporated the material properties and results of the field testing. The room geometry design was both judged and observed to be stable, hence mining commenced.

Jan 1, 1977

By A. W. Khair

This paper presents an analysis of surface subsidence characteristics in room and pillar mining using physical models and laser holographic interferometry (holometry). The analysis included the effect of various geometric parameters and different overburden materials (sand and gelatin) and resulted in the formulation of a more realistic model material for laboratory simulation of typical geologic overburden. Previous work using this technique involved the use of sand to model over- burden and detailed results are presented elsewhere (1). The main emphasis of this work was to develop a gelatin based mixture which would provide a better model. Initial work during the development of this model included testing various ingredients and monitoring the time dependent characteristics of the model, such as the surface penetration resistance. This value indicated changing deformability/ridgidity of the model with time. Once several models had been developed, holometry techniques were applied. Initial tests showed that the stiffness of gelatin created a bridging effect over the mine models, thus restricting deformation. At this point, a 0.5 inch (1.27 cm.) layer of sand was placed directly over the mine model with the gelatin mixture on top. The approach was to model different zones of overburden movement that exist as an extraction occurs (2). The sand would represent the caved and fractured zones which occur above the excavated area. The gelatin models the continuously deformed zone which occurs between the fractured zone and the surface. Holometry techniques applied to this model yielded successful results.

Jan 1, 1986

By M. P. Hardy, C. J. H. Brest van Kempen, H. N. Maleki

To evaluate the influence of uniformly tensioned roof bolts on roof stability, mechanically anchored roof bolts were installed using the conventional bolter and a specially developed thrust and torque controlled retrofitable box mounted on a bolting machine. Thirteen thousand bolts were installed over 19 crosscuts in a 4 heading development in an operating coal mine. Geological , bolt and mine parameters were recorded at bolt installation, and bolt tension histories, roof sag and other changes evident in the rooms, crosscuts and intersections were recorded over a 2 month period. In all, 24 variables and 11 responses were quantified at 67 bolt clusters. These data were analyzed statistically to determine the significant variables influencing roof stability. As the mine development was safe and stable during the monitoring period, roof sag after two months was used as an index to quantify "stability." The variables of significance were shown to be coefficient of variation of bolt tension, bolt anchorage capacity, roof lithology, roof shape, standard deviation of bolt tension, and dip of roof lithologies. It was concluded that of the variables with which the mine operator has control, bolt tension uniformity was the most significant parameter at this mine. Other variables, such as intersection type and time between mining and bolting , were not significant, whereas, some other potentially significant variables such as horizontal stress or roof joint frequency did not vary sufficiently for their influence on stability to be evaluated.

Jan 1, 1986

By John Wiebmer

Six industry trends will have significant effect on the way mining equipment is designed and supported in the years ahead: 1. MINING IS MIGRATING TO LESSER DEVELOPED PARTS OF THE WORLD The global recession of the early 1980's drove down commodity prices and intensified cost competition. This caused a fairly dramatic trend in mining away from higher cost operations in developed countries to richer, lower cost deposits in developing countries. Miners operating in lesser developed parts of the world will place higher value on rugged, durable designs that can live in more difficult and sometimes abusive conditions. They need engines and power train systems that are more tolerant of a wide variation in fuel quality and oil specifications. They'll require machines that are simpler to operate, simpler to maintain, simpler to troubleshoot and simpler to repair. And they'll require creative means of support in getting technical information, parts and components to remote operational sites. Mining equipment in the future will be more durable and simple than it is today, and product support will grow in importance as purchasing criterion. 2. THE MINING INDUSTRY IS CONSOLIDATING An intense amount of corporate acquisition and industry consolidation activity is occurring, to the point that today just 50 mining companies account for 55% of the western world non-fuel mineral production. Consolidation will continue, leading in the future to an industry structure weighted heavily toward a few key global mining houses.

Jan 1, 1993

By Todor P. Stefanov

The thermal draught within ventilation networks of underground mines depends to a great extent on the shafts depths and degree of change of ventilating air density. When the topology and space orientation of a ventilation network are constant, the dynamics of thermal draught is determined mainly by the variations of the heat- and mass-transfer processes in the openings. This conclusion follows from the well known basic theoretical notions about the thermal draught-aerostatics and thermodynamics [1]. Quantitative evaluation about the influence of heat- and mass-transfer processes on dynamics of thermal draught could be made through: direct mine measurements, special experiments and with the aid of mathematical models. The first two methods produce sufficiently accurative results, however it is very difficult to perform such studies, particularly when these processes are evaluated within a large scope and multifactor aspects. Mathematical models of thermal draught allow to overcome easily these difficulties. The degree of accuracy of results, obtained by this method, depends to a great extent on the degree of approximation achieved by the model to the real heat- and mass-transfer processes. In this paper, with the aid of Bulgarian developed method, algorithm and computer program V WT-4 - for complex evaluation of ventilation parameters in active mine ventilation networks [2], the authors investigate some changes in the thermal draught. Basically, the method is an iterating evaluation of an open set of equations, which represents relationships between the following basic parameters of a mine ventilation network: [ ]

Jan 1, 1980

By John W. Goth

This article, though not common feature material, should be of reader interest. Goth made this presentation as the keynote address at the 19th Annual Intermountain Minerals Conference in Vail, CO, in August. Introduction Working backward, what is an LDC? LDC stands for Less Developed Country. LDCs play a dynamic role in world supply and demand of basic materials. They occupy an equally important position in international marketing and finance. I will explain later some of my concerns with LDCs. First, I want to address an issue I think is of equal or even greater concern. Mining and High Technology Unfortunately, many people believe that America must make a decision now between being a smokestack-based economy or a high-technology-based economy. Some would have you believe that smokestack America is dead. Our only option is to turn to high technology, in a manner similar to countries such as Japan. Presumably, when we talk about high-technology industries we envision organizations that came into being within the last decade or so and incorporate microelectronics, biotechnology, and interconnected computers. The entire workforce is clad in lab coats and there are few employees in proportion to the work performed. High-technology industry is not labor-intensive work thanks to the efficient robots used. On the opposite side are smoke-stack industries, that we presume include the older, basic industries such as mining, agriculture, iron and steel manufacturing, ship-building, auto manufacturing, and nearly all forms of construction. These industries are judged to be labor intensive, requiring unsophisticated and untrained employees who succeed by the sweat of their brows rather than by advanced degrees in mathematics and physics. If these are indeed the presumptions about high technology versus smokestack industries, then I submit that those presumptions are a disaster. They are wrong and far from the truth. Smokestack industries, such as mining and the others mentioned, are indeed much older than some of the recently founded high-tech industries. But this does not mean that those smokestack industries are low-technology industries. On the contrary, American agricul¬ture is a very high-technology industry whose crop yields are the envy of the entire world. Mining uses virtually all of the advances available through modern technology. Far too many opinion leaders still envision mining as Humphrey Bogart and John Huston in the movie Treasure of the Sierra Madre. Yet there are many who hold the opinion that our basic industries are dead and that this country's future depends on specialized high-technology industries and services. That is tantamount to announcing we will continue to build space shuttle vehicles, but we no longer need launching pads and landing fields. The point is, we should not be wasting our time talking about "new" industries and "old" industries. We should devote our time and effort to industries that are effective and efficient in meeting our needs, in contrast to industries that are not effective and efficient in meeting our needs. Less Developed Countries That leads me to some of the problems I perceive with policies regarding the previously mentioned LDCs - Less Developed Countries. Far too many people do not realize that many of the smokestack industries being lauded in Less Developed Countries are being operated at a loss and to the detriment of worldwide industry. And the losses incurred

Jan 12, 1983

By Pieter Barendsen, Olivier Dubugnon

INTRODUCTION There are three fronts on which development efforts are being concentrated to extend the application domain of Tunnel Boring Machines (TBM), which is potentially very large - Assessment of a reliable prediction method, including machine-rock interaction and geological characterisation, so that the boring system can be designed properly and the costs remain in the predicted range for each given tunnel project. - Development of lighter, more flexible and more controllable machines to be applied in shorter, deeper tunnels or roadways, such as required in mining. - Reduction of cutter and machine costs when excavating hard rocks or difficult grounds, in developing improved tool materials, cutting geometries and tunnelling systems. The above three lines of development have a common, critical requirement: to have a reliable set of design rules to optimize the machine specifications from the knowledge of rock and geological parameters and working requirements. This optimization can only be done if a model sufficiently sophisticated is made available, able to take into account the numerous factors influencing the TBM advance , and being interactive enough to achieve the optimization.

Jan 1, 1985

By Songlin Ye, Frank Su

"Recycling valuable metals from waste streams has become increasingly important to the mining and smelting industry in China due to resource depletion and environmental concerns. Predicated on multiple large scale metal recovery operations designed by BQE Water at active mines in the Jiangxi Province of China, this paper presents a case study demonstrating recovery of zinc and copper from the waste stream at a major gold smelter in the Shandong Province of China. One of the issues facing the smelter is the lack of a cost-effective and robust process to recover zinc from the acidic process waste stream. As such, significant amounts of zinc-containing wastewater are neutralized with lime, resulting in not only the loss of zinc metal but also the generation of large volumes of sludge. In the case study, a sulphide precipitation process is chosen to selectively recover zinc and copper from the wastewater, in the form of commercial grade metal concentrates that can be sold as regular concentrates at the going market price. In the current project phase, over 2,500 tonnes of zinc metal and 40 tonnes of copper metal can be recovered on an annual basis. This not only generates revenue to offset waste treatment costs, but also eliminates significant amounts of sludge that would otherwise require storing and further disposal if the metals are not recovered.Introduction / Background With resource depletion becoming a global concern and environmental regulations becoming increasingly strict, companies in the mining and smelting industry are actively seeking technologies to maximize resource recovery and provide concurrent minimization of waste residue production from operational activities. Mining and smelting companies have typically used lime neutralization as the primary method to reduce metal concentrations from mine waters prior to reuse or discharge to the environment. However, this process creates large volumes of metal laden sludge with long-term liabilities in the form of ongoing storage and management (Zinck et al 1997). Recovering metals of value from mine water not only reduces sludge volumes and the costs of associated liabilities, it produces a commercial grade metal concentrate that can be sold to generate revenues to offset treatment costs. ChemSulphide® is a sulphide precipitation process developed by BQE Water that has been successfully applied at mine sites in the Jiangxi Province of China to remove and recover copper from acid mine drainage. The success of these copper recovery water treatment plants demonstrates both the economic and environmental benefits of recovering residual metals from mine water and provides reference for the copper and zinc recovery project at a gold smelter in the Shandong Province that is the subject of this case study."

Jan 1, 2017

More than 5,300 mining professionals from around the world attended the SME Annual Meeting and Exhibit, March 1-3 in Denver, CO. Seventy three technical sessions highlighted innovative technologies and applications for the development of mineral resources. And the exhibit featured 421 companies worldwide and 632 exhibit booths. The 1999 SME Annual Meeting had 10% international attendance Professionals from outside the United States were guests at the first SME International Reception. Other meeting highlights included the Keynote Session. This pivotal session examined the international experience of North American-based companies. Speakers presented their perspectives on international explorations and operations. Keynote speakers included Robert Buchan, Chairman an( Chief Executive Officer, Kinross Gold; Dave Baker, Director Global Mining Project Management, Caterpillar; and Leendert Krol, Vice President International Operations Newmont Gold. Ihor Kunasz, 1998 SME President, made the introductory remarks.

Jan 1, 1999

By M. A. Bouchat

The Kipushi deposit, where the Prince Leopold Mine has been installed, belongs to Union Miniere du Haut-Katanga and is located in the Belgian Congo, 20 miles SW of Elisabethville, at the vicinity of the Northern Rodhesian Border. The deposit is of the hydrothermal metasomatic vein-type; mineralisation took place, through the limestone of the, lower Kundelungu. This is a special fea¬ture of the deposit, compared to the other copper deposits of the neighbourhood, both in the. Belgian Congo and in Rhodesia. Actually, the primary mineralisation of these other deposits; is directly related to the stratigraphic systems: schistous dolomitic in the Belgian Congo and Roan in Rhodesia. Both facies are older than the Kundelungu and separated from this formation by a tectonic cataclysm. The valuable elements occuring at Kipushi are principally copper; and zinc. The deposit also contains smaller quantities of lead, precious metals and other elements including germanium.

Jan 1, 1960

By Steve Kral

"Gold rush" is usually associated the western United States - California, Nevada, and Colorado. The southeast section of the nation is known more for its rice, textiles, tobacco, indigo, and cotton. This area, though, is where it all began with gold in this country. The United States' first gold rush, in fact, is said to have started with the discovery of a 7.7-kg (17-1b) nugget in the Piedmont section of the Carolinas in 1799, some 50 years before the rush to California. The Carolina gold rush continued intermittently through 1942 when the Federal Government shut down all gold operations. Strong gold prices throughout the early part of this decade and new extractive technologies spurred a small resurgence of gold operations in South Carolina. Mind you, this is not Nevada with its flood of geologists and mining companies. Nor are there any 7.7 kg (17 lb) nuggets being discovered. But Ridgeway Mining Co., a joint venture between Kennecott Corp. and Galactic Resources, has set about mining 51 Mt (56 million st) of low-grade ore containing an estimated 43.5 t (1.4 million oz) of recoverable gold. The open pit, carbon-in-leach operation is located near the town of Ridgeway in South Carolina, about 32 km (20 miles) north of Columbia. Carolina gold North and east of Ridgeway, Piedmont Mining Co. operates the historic Haile gold mine near Kershaw, SC. And Brewer Mining Co. operates the nearby Brewer deposit. Between 1829 and 1942, South Carolina gold mines produced 10 t (318,800 oz) of gold. It all began in 1799 when Conrad Reed, son of a German immigrant farmer, found the 7.7 kg (17 lb) nugget in Little Meadow Creek, NC. His father thought the rock was worthless and used it as a doorstop, so the story goes. It took nearly three years before Conrad's father decided his doorstop was indeed gold. Gold was later discovered in the Greenville district of South Carolina. And, in 1828, Benjamin Haile discovered gold in a stream that ran through his property in Lancaster County, SC. Haile's mine became South Carolina's most famous and most productive gold mine, producing more than 7.8 t (250,000 oz). At first, miners worked the stream beds of Haile's property. Later, lode deposits were discovered on slopes alongside the creeks. They would lease 4.6 ml (50 sq ft) lots and mine as deep as 7.6 m (25 ft). During the Civil War, the Confeder-

Jan 1, 1989

By F. Montgomery Lyon

Pyritic sulfur in coal occurs as discrete mineral particles, and its liberation and physical rejection is the primary target for coal desulfurization. An acceptable solution to the pyrite removal problem from fine coal is not found in the standard methods of coal cleaning such as jigging, heavy-medium separation, tabling, and hydro-cycloning. Although fine coal is an ideal size for froth flotation, this method, as currently practiced is also unsuitable as the fine pyrite usually floats with the coal. One possible solution to this problem may be the froth flotation of pyrite from coal. This reverse flotation scheme would have the major advantage of removing both free pyrite and locked pyrite-coal combinations. With this possibility in mind, we have, as a first step, compared the flotation and adsorption. characteristics of an ore-pyrite and coal-pyrite with potassium-ethyl-xanthate as a collector 1 Related Research. The action of ethyl-xanthate on coal has been studied 2 by Horsley. He measured the contact angles of coal in distilled water and in the presence of purified ethyl-xanthate. The results indicated that the xanthate was not adsorbed by the coal. Additional contact angle data were obtained to determine the effects of cupric, ferric, and ferrous salts on the system. Then either the ferric or cupric salts were in, solution with the xanthate, there was an increase in the natural contact angles of the coal. This indicated that these heavy metal ions activated the flotation of the coal with xanthate. However, ferrous iron did not act as an activator. Horsley stated that the most attractive explanation was that the xanthate is oxidized to dixanthogen in the presence of the ferric and cupric ions.

Jan 1, 1971

By L. K. Holder

"The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund, mandates evaluation of remediation alternative using nine criteria: (1) overall protection of human health and the environment, (2) compliance with ARARs (applicable or relevant and appropriate standards), (3) long-term effectiveness and permanence, (4) reduction of toxicity, mobility or volume, (5) short-term effectiveness, (6) implementability, (7) cost, (8) state acceptance, and (9) community acceptance. Many states have adopted these or similar criteria for remedy selection under state laws. Although not explicitly addressed in the CERCLA criteria, consideration of sustainability can be incorporated into these criteria. This paper explores how sustainability can be evaluated for remedy selection using the CERCLA criteria. INTRODUCTION Sustainability considerations can be incorporated into all phases of site remediation: • Site investigation (remedial investigation). • Remedy selection. • Remedial design. • Remediation construction. • Operations, maintenance, and monitoring. This paper focuses on remedy selection. Many have looked at remedy selection using sustainability criteria. However, CERCLA and corresponding State programs require remedy selection using mandatory criteria. This paper shows how sustainability can be explicitly considered using the mandatory criteria. REVIEW OF CERCLA CRITERIA First, we review the definitions of the CERCLA criteria. We then explore how sustainability criteria can be fit into the CERCLA criteria. Overall Protection of Human Health and the Environment This criterion addresses the degree to which each alternative is protective of human health and the environment, considering both long-term and short-term risks. Overall protectiveness is a ""threshold"" criterion, in that alternatives that do not achieve adequate protection of human health or the environment are eliminated from further consideration. Evaluation of this criterion is derived from the evaluation of the other criteria (e.g., long-term effectiveness and permanence, and short-term effectiveness). It is not an independent criterion, but more a summary of the overall evaluation."

Jan 1, 2015

By Laurence B. James

The California Department of Water Resources is concerned with the development, distribution, and protection of the State's water resources. Geologic activities of the Department relate to planning, construction, and operation of water projects, supervision of the safety of over 900 dams under state jurisdiction, and investigation and control of ground water supply. The Department is engineering oriented, and the role of the geologist is to assist with the solution of engineering problems. Some of these problems require the integration of many talents, including not only those of geologists and engineers, but also those of economists, lawyers, seismologists, chemists, geophysicists, and hydrologists, Frequently, a task force of several disciplines will attack a problem as a team.

Jan 1, 1965

By Warnie Flint

According to statistics compiled by the National Safety Council, US Bureau of Mines, American Medical Association, and other agencies, accidental injuries cause more deaths than all the leading diseases. No one is immune to an accident. Probably the best way to describe an accident is to say that it is an unexpected happening. The automobile driver is not expecting a terrifying crash, the electrician does not expect to be electrocuted, nor is the coal miner expecting the roof to fall on him. All personal injuries will not result in death. There is a multitude of victims who are living proof of what accidents can mean to an individual-victims who are blind, paralytic, missing arms, legs, etc. In most instances the earning power of these individuals is gone, and they are utterly dependent upon family or welfare. For many years there seemed to be an attitude that prevailed in industrial America that accidents were inevitable, and that so many fatalities and injuries should be expected. This, of course, was utter nonsense. Since the birth of such organizations as The National Safety Council, American Society of Safety Engineers, and. the US Bureau of Mines, much progress has been made in reducing accidents. The enactment of compensation laws greatly contributed to the progress that has been made. Does this mean that all accidents can be prevented? Unfortunately, it does not. Human psychology indicates that men will work unsafely or perform unsafe acts for the following reasons : 1) Lack of knowledge or skill. 2) Conflicting motivations, such as: (a) to be more comfortable, (b) to save time or effort, (c) to be accepted by a group. 3) Physical or mental condition. Nearly everyone desires his own safety, but not all individuals are willing to do what they know to do to insure their own safety.

Jan 1, 1981

By John L. Schroder

The design of an underground mining operation requires the integration of transportation, ventilation, ground control, and mining methods to form a system which provides the highest possible degree of safety for mine personnel; the lowest cost per ton of product; the most suitable quality of final product, considering its intended use; the maximum percent recovery of the reserve, consistent with cost and subsidence rights; and the minimum disturbance to the environment. The selection of mining method is generally the controlling factor in overall mine design. Some important considerations in the choice of mining method are : 1) Depth of cover over the coal seam. 2) Strength and thickness of rock strata in the overburden. 3) Characteristics of the coal seam, including thickness, nature and location of impurities or irregularities, dip (or pitch), nature and direction of cleavage, hardness, and structural strength of the coal. 4) Nature and strength of the immediate roof (top) over the coal seam. 5) Nature and strength of the floor (bottom) under the coal seam. 6) Presence and amount of explosive gas (methane). 7) Quantity of water likely to be encountered in the mining operation. 8) Any previous or concurrent mining in seams above or below the coal seam to be worked. 9) Any restrictions on recovery required for subsidence control. Topographical and geological reports and maps of the area are usually available from state and federal geological surveys, and contain excellent general information to guide more detailed investigations. Exploratory drilling, and the plotting and analysis of the information thus obtained, are essential steps in any development program, and aid in the correlation and evaluation of information gained by other means. Other good sources of information are operating coal mines that may be in the same seam in nearby properties. Such mines may indicate in advance much about roof control, drainage, ventilation, and other mining problems.

Jan 1, 1981

By Kenneth G. Knight, Frank L. Lynch

It's 12:30 A.M. The day before had been a long one with problems ranging from proper application of shotcrete during cold weather and the follow-on precautions for curing, meetings with city officials to avert a job shutdown because traffic wasn't being maintained properly and finally a briefing before METRO's General Manager to bring him up to date on projections for meeting the operational date of June 1975. The phone rings and Officer Jones of the Park Police says "Mr. Lynch, this lady in the apartments overlooking the jobsite is complaining of noise and she wants the job shutdown". "Officer Jones, have you called the Project Manager or the Resident Engineer?" "Yes, sir, but there is no answer!" "O.K., Officer, I'll check it out." In calling the job, I can only get the guard, because the inspector is in the tunnel. After some time, the guard calls back and says he doesn't know the way down into the tunnel. I have since had a difficult time believing that one. In the interim I finally reached the Resident Engineer and explained the situation. And finally at 1:30 A.M. the inspector called the Resident to say that the Park Police stopped the job at 1:00 A.M. because we didn't respond promptly. A similar situation had occurred some 2 years previously. With great expectation, noise specifications were developed to correct the earlier situation that had occurred. These newly developed specifications were in force at the time of this most recent shutdown. Common sense would tell you that even though we had developed and implemented, we believe, some of the best and most practical noise specifications in construction practice today, we had not enforced them. What caused the shutdown - a noisy

Jan 1, 1974