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By David Hopkins, Steve Klein, Bradford Townsend, Ed Sum, Derek Penrice

INTRODUCTION The Transbay-Caltrain Downtown Extension (DTX) Project involves the construction of an approximately 1.5-mile rail line that will extend Caltrain commuter service and the future California High Speed Rail system into downtown San Francisco. The underground rail extension will be constructed by mined tunnel and cut-and-cover methods. Tunneling challenges include difficult ground conditions, low rock cover, the presence of historic buildings along the alignment, and the large tunnel span, ranging from approximately 50 to 65 feet. Three mined tunnel construction methods were evaluated: the Stacked Drift Method, the New Austrian Tunneling Method/Sequential Excavation Method (NATM/SEM), and Tunnel Boring Machines (TBM). This paper describes the challenges presented within the mined tunnel section, and summarizes the evaluation of tunneling methods that led to the selection of NATM/SEM. PROJECT OVERVIEW The existing Transbay Terminal opened in downtown San Francisco in 1939. This facility is antiquated, and does not meet current building seismic safety standards or the transportation needs of the Bay Area. For these reasons, San Francisco voters approved Proposition H in 1999, which proposed to construct a new or rebuilt regional transit center at the site of the existing terminal and extend Caltrain commuter rail ser-vice to the new transit center. The new transit center is the hub of the Transbay Transit Center (TTC) Program, which will greatly enhance regional transit service by providing connectivity for six Bay Area transit providers at one facility. The program will be the largest inter-modal centerwest of New York City. The TTC Program is comprised of two major projects, the Transit

Jan 1, 2007

By B. J. Dave, Ashok J. Desai, Allen J. Hulshizer

This paper presents various design and construction considerations involved in developing an underwater installation of lined, large diameter shafts not known to have been previously accomplished for the diameter size, depth or ground conditions identified with the Seabrook Power Station. Outlined approach provides for driving tunnels independent of shaft sinking operation, permits the use of prefabricated shaft lining and incorporates a safe dry tap method for connecting the shafts to the tunnels. INTRODUCTION The Seabrook Power Station, located two miles inland from the Atlantic Ocean, at Seabrook, New Hampshire, is a two unit, nuclear powered, electric generating plant, each unit having a capacity of 1150 megawatts (electric). Typical to all steam driven generators is the requirement for large quantities of water. Requirements for the Seabrook Plant will be met by intaking and discharging approximately 850,000 gpm of ocean water at a considerable distance from the shore line in water depths that render the environmental impact inconsequential. Obtaining, conveying and discharging such large quantities of water represents a major undertaking, particularly under today's environmental controls. Tunnels are well suited to reducing the environmental impact at the Seabrook site by conveying the water about 250 feet deep under the salt marsh (a valuable ecological feature) and under the beach well out into the ocean without any noticeable ground surface disturbance. An alternate approach utilizing trenched piping would have created some disturbances and was environmentally less desirable. The tunnels connect to intake and discharge

Jan 1, 1976

Software exhibitors at MINExpo will feature the newest, the best, the most comprehensive computer-based tools available to get minerals from the ground to the market. From the ?cloud? to the pit, the variety that will be featured is almost limitless ? a digital tool for every phase of the mining lifecycle. Blue Sky Network SkyRouter brings the Blue Sky Network to the cloud. Using its interactive Web portal, SkyRouter, with detailed mapping and integration with Google Earth, the Blue Sky Network links enterprises to personnel and assets anywhere on earth through Iridium satellites. The cloud-based solution is designed to support connectivity with remotely dispersed mobile assets, including Blue Sky?s dual-mode GSM and Iridium tracking and communications services. This enables seamless connectivity with assets in problematic cellular reception areas, where only 10 percent of the Earth is covered, and in remote locations.

Jan 1, 2012

By Fred D. Fox

Introduction Abandoned mill tailings deposits can be found throughout the northern Black Hills of South Dakota, indicative of mining activities that originated during the great gold rush days of 1875. The Refuse Act of 1899 attempted to regulate the deposit of debris from mines and stamp works. But, in most cases, huge volumes of mine and milling wastes were disposed of in ways no longer considered environmentally acceptable. Restoration of gold mill tailings deposits is a relatively new practice to the Black Hills area. This discussion will present an overview of the environmental setting, environmental problems associated with past tailings disposal practices, practices being implemented to solve these problems, and prospects related to present the future tailings disposal practices. Environmental Setting An understanding of climatic characteristics, geology, surface and ground water hydrology conditions, and the physical and chemical characteristics of selected mill tailings deposits will aid in understanding environmental problems associated with tailings disposal and restoration. Climate The Black Hills region is in the middle latitudes, which have a

Jan 11, 1984

By Lee W. Abramson, William H. Hansmire

The H-3 Project is planning, design, and construction of a 10-mile (16 km)-long final segment of new highway that traverses the Koolau mountain range in Oahu. Interstate H-3 traverses North Halawa Valley on one side of the Koolau Mountains and Haiku Valley on the other side. The project includes a tunnel through the mountain range. The one-mile (1.6 km)-long twin-bore Trans-Koolau Tunnel will have two lanes in each direction. The total roadway width including shoulders in each bore will be 38 ft (11.6 m). The geologic and geohydrologic conditions along the alignment present a variety of tunneling problems. Geologic conditions consist of volcanic materials deposited generally in fairly thin basaltic layers. These volcanic materials generally weather down to "MH" soils which are compressible but relatively strong. Perched ground water that is recharged by heavy rainfall is present in the mountains. The paper presents results of initial geologic surveys and exploratory boring, and plans for exploratory tunneling and testing programs. A site specific classification method developed to characterize the weathered profile is presented.

Jan 1, 1989

By S. Cotten

The regulations for current coal mine refuge alternative (RAs) require that there be sufficient life support to sustain survival of the maximum number of RA occupants for a minimum of 96 hours. This minimum duration assumes that rescuers can access the RA through the mine within four (4) days of the onset of the mine emergency. But what if mine rescue teams cannot reach the miners within the RA before the RA air supply is severely limited or exhausted? What could be done to extend the duration of the RA life support capability into the 97th hour and beyond? In addition, what might be done to enable more rapid rescue of the miners if they could not be reached through the mine in a timely manner? This paper describes a systems approach to address the potential need to extend the duration of RA life support beyond current design limits. New capabilities that need to be developed in advance of such a dire need include more reliable emergency communications, highly mobile and efficient drilling rigs, enhanced directional drilling techniques, and a standardized RA external life support interface along with RA internal design modifications to accommodate use of an external supply. The following sections describe the need, intent, and technology gaps associated with each of these capabilities. Government agencies and the mining industry should consider initiation of a program to investigate, design, and develop effective means of extending the current 96-hour time restriction on coal mine refuge alternative life support. The development process should begin with a focused study to refine the overall operational concept, investigate the current state-of-the art of critical technologies, identify specific technology development priorities, and make recommendations for a development program to provide in an organized, efficient, and timely manner a solution for extended refuge alternative life support and occupant rescue.

Jan 1, 2011

By Tony S. Calayag

Throughout the mining industry today, new bearing materials - ZA* high-performance zinc-aluminum alloys - are reducing costs of maintaining and rebuilding a wide range of equipment. As replacements for bronze bearings, installed in original equipment at the plant or during maintenance and repair operations in the field, the zinc alloys frequently provide better or equal performance at lower cost. The ZA Alloys The ZA alloys are a family of three high-performance zinc-aluminum alloys that compete in cost and performance with cast iron aluminum and bronze. The growing number and uses testifies to the versatility of these alloys and is encouraging their consideration in a wider range of applications. The ZA alloys are referred to as ZA-8, ZA-12, and ZA-27, the numbers corresponding approximately to the percentage of aluminum each alloy contains. ZA-8 is a permanent-mold casting alloy and is usually selected for decorative purposes; ZA-12 provides both performance and cosmetic benefits; ZA-27 offers the greatest functional strength. The term high performance ZA alloys distinguishes them and their improved engineering properties from traditional zinc die casting alloys. Maintenance Savings At its mine in Timmins, Ontario, Kidd Creek Mines Ltd. operates over 40 Joy VCR- 150 crawler-mounted air-powered rock drills. Most of the drill components undergo severe stress as the drill batters through the under-ground rock. As the components wear, the drill bits wobble; when the wobble becomes excessive, the drills are rebuilt. In the gear train, which rotates the drill steel, there are three planetary gears with - historically - bronze bushings. Since the planetary gear bushings are wear items, they are routinely replaced during overhaul. The bronze planetary gear bushings (three bushings per assembly) were replaced up to five times annually. With 43 drills in use, bushing consumption approached 600 per year. At the manufacturer's replacement part cost, the 600 bushings and gears would cost more than $20,000 a year. Even though a major saving was achieved by having the bronze bushings manufactured locally, the 600-unit annual usage provided ample incentive to investigate other ways of lengthening drill life and reducing the part costs. One approach was to consider using a bushing material that offered good bearing properties, but was lower in cost. About three years ago, ZA-12 zinc-aluminum casting alloy, costing less than half as much as bronze, was evaluated and selected for testing. One hundred ZA bushings were manufactured and placed in service as the drills came in for rebuilding. At the next rebuild the "drill doctor" (drill maintenance mechanic) noticed that, although the bronze bushings were completely destroyed, on occasion the zinc alloy bushings were not. In addition, he noted that some of the ZA bushings showed less wear than the bronze bushings. Because the bushings were changed routinely during each overhaul, the actual operating life of each bushing was not determinable. Therefore, it was not possible to statistically compare the life of the ZA bushing against the bronze. However, the desired life of the part was from overhaul to overhaul. So the ZA alloy obviously met the objective, giving equal or better life than bronze at a significantly lower price. Based on the favorable results of the testing under actual operating conditions, Kidd Creek maintenance personnel decided to switch permanently to the ZA bushings for rebuilding the VCR-150 rock drills. Original Equipment Application As one of the leading companies marketing the ZA alloys, as well as a zinc -copper-silver mining company, Kidd Creek is interested in developing applications for the alloys by original equipment manufacturers such as joy Manufacturing. Kidd Creek marketing representatives provided joy with information on the Timmins mine tests, along with ZA-12 bushings for evaluation and testing. Based on this information, joy installed ZA bushings in 12 new VCR-150 units and delivered them to customers for use in such areas as granite quarries and copper, lead, zinc, and limestone mines. During the following year, joy engineers closely monitored repair reports to verify the performance of the ZA part. The engineers' findings convinced them of the advantages of ZA-12. As a result, joy now uses ZA-12 bushings in the manufacture of its VCR-150 air tools. Advantages for Casters and Users In the foundry, the new alloys have proved their castability and profit potential in sand and metal permanent-mold processes, as well as the new graphite permanent-mold gravity casting process. The energysaving, pollution-free and ease-of-machining benefits they offer are important to all of these processes. Most recently, the high-performance alloys entered the arena of cold-chamber die casting, where they provide properties beyond those of

Jan 7, 1983

By S. S. Peng, C. T. Holland

Mountain Top Removal (MTR) mining started in West Virginia nearly thirty years ago. This surface mining method can extract multiple coal seams as thin as a few inches thick with total recovery and minimum rock dilution in very steep mountainous terrain. It is highly efficient even if coal seams are in close proximity and small in aerial extent. Consequently, MTR has been widely used in the Central Appalachian Coalfield (mainly Kentucky, Tennessee, Virginia and West Virginia) for the past thirty years with great success. In that respect, there has been no demand for research and little scientific research has been performed to investigate its impacts on the surroundings in the history of MTR mining. However, in the past two years the debate over the MTR mining has grown quickly and in times become very intensely. This paper describes chronologically the issues raised by various parties, legal actions, its impacts on mining permit application and research projects developed to address the issues.

Jan 1, 2000

By R. C. Burton

One of the major problems encountered with recirculatory breathing apparatus presently used by mine rescue teams is that the inspired air becomes uncomfortably, and often dangerously, hot. This is also true with self-rescuers. It is well known that man can tolerate very high dry-bulb temperatures if the wet-bulb temperature is low, but not vice- versa. The maximum tolerable, wet-bulb temperature is about 42 °C (108 °F). A continuously inhaled wet-bulb temperature above this value can cause irreversible damage to the throat and lung tissue, and wet-bulb temperatures close to it cause extreme discomfort (1) and seriously retard the capability of the man to perform useful work. A theoretical analysis, combined with experimental results, has shown that it is the carbon dioxide absorbent that is the major cause of high wet-bulb temperatures of the inspired air in the Siebe Gorman Proto 4, and in the Draeger BG 174 apparatus, both of which are used by rescue teams on South African mines (2). In the Proto 4 apparatus, the absorbent for the carbon dioxide is soda lime (calcium hydroxide). The German Draeger BG 174 also uses this absorbent but under arduous conditions such as in hot environments (50 °C, 122 °F), the use of an alkali absorbent cartridge is recommended which consists mainly of caustic soda (sodium hydroxide). Lithium hydroxide is used in some apparatus in the United States. It is clear that different absorbents will produce different quantities of heat and moisture for a given rate of absorption of carbon dioxide. The proportion of this heat and moisture which is transferred to the user depends upon how much can be removed from the recirculating air between the absorbent and the mouthpiece. This paper discusses the present methods of heat removal and describes the design and test results of a prototype evaporative cooler.

Jan 1, 1980

By Jean Habimana

Complex and distinct geological units spread along the 7-mile long 30-ft inside diameter Upper Rouge Tunnel CSO Control Project in Detroit, Michigan. Its construction is divided in two tunnel construction packages: The South Tunnel, to be driven in finely laminated weak TG Limy Shale, will be excavated by a shielded TBM with precast concrete segmental lining, while the North tunnel, predominantly in a relatively more competent geologic formation Antrim Shale, will be excavated by a main beam TBM with a two-pass lining system. The adits and deaeration chambers will be excavated by sequential excavation method. This paper addresses the process of selecting excavation methods and lining systems for shafts, tunnels, connecting adits, and deaeration chambers.

By R. A. Gee, G. B. Ashton, S. T. Warren, P. N. Groves

Northside Storage Tunnel provides 500 megalitres (Ml) (130 million gallons) of storage capacity to capture stormwater/sewage overflows into Sydney Harbour. The6.6 m diameter TBM driven tunnel traverses Middle Harbour 85 m (280 ft) below sea level and through a sandstone/shale rock mass, highly disturbed by stress relief, 20 m(65 ft) beneath the base of the sediment filled palaeochannel. Target limits for inflow, groundwater drawdown and settlement of the valley beaches were achieved by systematic forward grouting from the TBM. Support included rockbolts, sets and shotcrete to carry rock loads, control block instability and spalling and to provide durability and serviceability. This paper describes the tunnelling and grouting works and their effectiveness.

Jan 1, 2001

By Cherie H. Tilley

The possibility of drilling oil wells from underground locations is not a new concept. It bas not been cost effective for the oil industry in the past and therefore disregarded. Today's state of the art in tunneling and shaft sinking greatly improves the potential for this type of oil field development scheme. This report presents a plan for providing a aeries of drilling bases and the design of the drilling location. The design minimizes the amount of excavation needed to develop the oil field and maximizes the use of rapid excavation techniques.

Jan 1, 1983

By Steve Kral

The domestic mining industry may be in the doldrums but there appears to be hope, at least from a regulatory standpoint. At least one US senator believes that the events of Sept. 11, 2001 made many citizens see the need for the country to become more self-reliant on its growing energy needs. Even before that tragic day, however, the Bush administration was making a strong push to open up more public land for energy and natural resource development.

Jan 1, 2002

By Christopher J. Bise

INTRODUCTION The transportation of men, supplies, and mined material from an underground operation is the connecting link between the mine plant and the surface plant. Unless the mine is accessed by a drift or adit, some form of hoisting system is necessary for slopes or shafts. This chapter will deal with the selection of wire ropes and hoists, two of the most important consider¬ations when designing a hoisting system for an under¬ground mine. WIRE ROPES General A wire rope is designed to transmit forces longitudi¬nally along its axis. Wire rope is used in a variety of mining applications because of its flexibility, high ten¬sile strength, and dependability. Shaft hoisting ropes and principal slope haulage ropes are usually custom-¬built; however, proper rope selection for slushers, car spotters, etc. should not be overlooked. Wire ropes for shafts and slopes, since they represent the life line for the mines, should be of the very highest quality improved plow steel. This quality is necessary to deal with the conditions of loading, winding, vibration, abrasion, and corrosion. Tables I and 2 display the specifications for the typical wire ropes used for mine haulage applications. The 6 x 19-class haulage rope is used for most hoisting where abrasion is not critical. On the other hand, where abrasion is critical, such as a slope application, 6 X 7-class haulage ropes are preferred. For other mining applications, manufactur¬ers' handbooks should be consulted. Selection The selection of a wire rope for a mining situation consists of simply applying appropriate safety factors to a calculated maximum rope pull and comparing the result to the listed breaking strength of the rope under consideration. Table 3 can be used for determin¬ing the minimum factors of safety for wire ropes. To determine the maximum rope pull, the following quantities must be known: the rope weight in pounds (x), the conveyance weight in pounds (y), and the weight in pounds of the load in the conveyance (z). These values are used to calculate the load due to gravity, the load due to conveyance friction, and the load due to rope friction. When these loads are added together, as shown in Eq. 1, the maximum (static) rope pull (RPS) can be derived:

Jan 1, 1986

By Rainer Kahrger

This paper is a follow-up to the paper presented at the SME meeting in April of 1996. Since then, the El Abra facility has been started up, 9 months ahead of schedule, and has processed about 45 million tons of ore and produced over 700 million pounds of copper. For those unfamiliar with the El Abra materials handling and leaching facilities, a brief overview of the facility is provided. The paper will then deal in detail with such aspects of Conveyor 103, the long regenerative overland conveyor, including: actual running resistance starting and stopping procedures emergency brake test at 10,000 t/h Additionally, we shall take the opportunity to report on a catastrophic culvert collapse in October 1996, which stopped the conveyor abruptly at full speed and under high load condition, causing a belt breakage. We would like to use this opportunity to thank the management of El Abra and Cyprus Amax for providing assistance and allowing us to present this paper. The El Abra team deserves a great compliment for building this one billion dollar facility in record time in a remote area of a high-altitude desert with no existing infrastructure, and for bringing it so quickly up to full operating capacity. The El Abra management had to assemble a completely new operator team. Considering the above circumstances, it took a great effort by all involved to achieve success. The official performance test which was required by the lending banks was successfully concluded in November 1997.

Jan 1, 1998

By K. Saikiran, A. R. Nalla

Longwall management, regular shield maintenance, and evaluation of ground control problems can be performed using real-time shield monitoring program. Based on real-time shield pressure data, evaluation of intensity and interval of periodic weighting, estimation of time-dependent pressure increase and the effects of geologic anomalies can be obtained. In this study, full-face shield pressure data of over 457 m (1,500 feet) of face advancement is analyzed to evaluate shield response in the presence of surface lineaments, floor undulations, and multiple main roofs. Shield pressure increase due to web cutting is also correlated with setting pressure during periodic weighting and normal time. In addition, time-dependent pressure increase rate on Sundays and holidays is also correlated with time average pressure and the location of previous periodic weighting.

Jan 1, 2000

By Thomas Marcher

Stanford Linear Accelerator Center (SLAC) is located in Menlo Park, CA. In order to allow for enhanced experiments, the current facilities required expansion. Tunnels were excavated through very weak sedimentary rock interspersed with uncemented zones (Ladera Sandstone) employing the principles of the NATM. The overburden var-ied from 10 to 80 feet. The paper addresses the characterization of Ladera Sandstone that can exhibit the properties of dense sand and weak rock. The paper focuses on the challenges that were encountered during the NATM initial support design and the construction phase including the geotechnical instrumentation, monitoring and design verification process in particular the excavation of the junction between access tunnel and the FEH cavern (49 ft wide by 32 ft high).

Narrow vein mining, with enough challenge and also where the cutting edge technology can be applied, is still a very important and exciting portion of the mining industry. Based on the deposit characteristics, the most flexible mining method, cut and fill, has been being tested mining this high grade Northern Nevada property, Hollister, since the year of 2008. In the last three years, 254,000 tons of ore were hauled out of the portal and 23,000 feet of development were excavated underground with the winning of several safety and environmental awards. Together with mine geology, the essential segments include mining cycle, ground control, ventilation, grade control and backfill method in cut and fill stopes were covered in this paper.

Jan 1, 2012

By S. C. Sun

A study(1) on the sulfuric acid extraction of alumina from some Pennsylvania ferruginous clays indicated that the published electrolytic method(2)(3) seems to be more efficient than the known chemical methods (4-9) for removing iron from the leach liquor. The main disadvantages of the chemical methods are the consumption of excessive amounts of reagents and/or the precipitation of prohibitive amounts of aluminum. In the electrolytic method, iron is deposited on the mercury cathode, while aluminum is not and remains in solution. This method, however, had been handicapped by the lack of an effective and economical way to purify the contaminated mercury cathode.(7)(l0). Described herein is a scheme for cleaning the mercury cathode, and for recycling the clean mercury back into the electrolytic cell. Armed with such an apparatus, the effects of applied potential, temperature, and operation time on the electrolytic separation of iron from aluminum sulfate solutions were determined. For the sake of comparing results, a term, removability, was coined to represent the percentage of iron amalgamated per unit height of electrolyte (cm.), per unit surface area of cathode (cm.2), per unit of operation time (second).

Jan 1, 1968

As metal prices fluctuated over the years, so too have the fortunes of many of those mining in Canada?s Yukon province. With a rich mining history that dates back to the Klondike gold rush of 1896 to 1898 and continues to thrive today, Yukon has experienced several ?boom-and-bust? cycles. However, during the world?s most recent mining ?bust? Yukon has held strong and has re-mained one of the world?s hottest destinations for mineral exploration. In fact, the area even exceeded forecasts in 2009, more than doubling last year. And the near-future looks just as bright.

Jan 1, 2010