Search Documents

By August V. Castelli

Drilling fluids have changed over the years from water and/or water frequently mixed with local clays to scientifically com- pounded materials (mud). This change has occurred due to changes in drilling methods from percussion to rotary: depth maximum from 21 m in the first oil well to more than 9 000 m; and variety in types of well or hole to gas, oil, water, and mineral exploration. Environmental concerns about the composition of the fluid as to heavy metals and oil on the cuttings has recently caused changes in the materials used in the mud. The drilling fluid should perform the following functions (Darley et al., 1980): 1) Carry cuttings from beneath the bit, transport them up the annulus, and permit their separation at the surface. 2) Cool and clean the bit. 3) Reduce friction between the drilling string and the sides of the hole. 4) Maintain the stability of uncased sections of the borehole. 5) Prevent the inflow of fluids-oil, gas, or water-from permeable rocks penetrated. 6) Form a thin, low-permeability filter cake which seals pores and other openings in formations penetrated by the bit. In addition to these, the fluid should: 1) Not injure drilling personnel nor be damaging or offensive to the environment. 2) Not require unusual or expensive methods of completion of the drilled hole. 3) Not interfere with the normal productivity of the fluid- bearing formation. 4) Not corrode or cause excessive wear of drilling equipment. A number of industrial minerals, chemicals, and other materials are used as additives in the drilling fluid to accomplish these functions. Industrial minerals make up the highest percentage of the additives in a drilling fluid. Drilling fluids are classified according to their principal components: water, oil, and gas. If the major component is either water or oil, the component along with the suspension of solids, cuttings and additives is referred to in the trade as a mud. The largest use of some industrial minerals, such as barite and bentonite, is in drilling muds. For other materials, such as gypsum and limestone, drilling usage is only a small percentage of total demand. RAW MATERIALS [Table 1] lists the industrial minerals used in drilling fluids, their form, specifications, and uses. Each raw material will be discussed as to its mineralogy, physical and chemical properties, and the location of major deposits with respect to drilling fluids. Attapulgite Attapulgite is a crystalline hydrated magnesium silicate clay mineral, prized for its viscosity in saline waters. The particles are needle-like rather than the platelets common to most clay minerals. The specific gravity is 2.5 and the Mohs hardness is 1 to 1.5. Attapulgite is one of the materials sometimes referred to as fuller's earth. The major producing areas in the United States are southern Georgia and northwestern Florida. It also is mined in Spain, Senegal, the Republic of South Africa, Turkey, India, and Australia. Barite Barite is crystalline barium sulfate. It has a high specific gravity for a non-metallic mineral, 4.5 when pure, and is used as a weighting agent. Generally, the specific gravity ranges from 4.20 to 4.35. It is relatively soft with a Mohs hardness of 3 to 3.5 and is not very abrasive. Barite is inert, non-toxic, and clean to handle. Common contaminants are quartz, iron minerals, gypsum, and calcium carbonate. If there is considerable gypsum in the barite, it will thicken the mud. The major deposits in the United States are in north central Nevada, near Battle Mountain. The major producing countries, other than the United States, are China, India, Mexico, the former USSR, Turkey, and Morocco. The major deposits in India and Nevada, and some in China, are stratiform, commonly quite pure bodies in bedded sedimentary rocks.

Jan 1, 1994

By E. F. Klein, R. L. Eacret

Introduction In contrast to the general type of crushing mechanism in which the crushing surfaces alternately approach and withdraw from each other, described earlier in this section, and continuous-pressure break¬ers such as rolls and roller mills that will be described in a later chapter, impact crushers load by striking pieces of rock while in free fall and hurling them at high speed against stationary surfaces. Because the impact crusher depends for its effectiveness upon high velocity, wear is greater than in the slower-moving jaw and cone¬type wear parts, and for this reason its use is strictly limited to rela¬tively soft, friable, and sticky rocks that are characteristic of many nonmetallic mineral deposits. A few of these are phosphates, lime¬stone, barite, clay, asbestos rock, and coal. However, several examples of their use on soft lead-zinc and precious metal ores have been known. Although the use of impact crushers is expanding today into the range of ores containing as much as 15-18% silica, Taggart16 set the practical limit at 5%, and in the 1940s and 1950s several installa¬tions in the US and western Europe exceeded the limits of economical maintenance and were quickly superseded by the slower-moving, con¬ventional crushers. A rock that tends to be plastic or bouncy in a jaw or gyratory crusher when the force is applied slowly to reach ultimate strength, may become brittle with rapid loading and thus increase the effective¬ness of the applied forces. For this reason it is to be expected that as the quality of hammers, grates, plates, and cages improves with advances in steel technology, the use of high-speed crushers of this kind will increase. Terminology Modern usage differentiates between the impactor and the hammer mill, the former relying primarily on the impact of hammers (fixed or free-swinging) and secondarily upon pieces striking one another or steel surfaces; the hammer mill relies on both the centrifugal impact force of free-swinging hammers and the attrition and shear action between these hammers and well-placed grates suspended at the bot¬tom just below the hammer circle. The hammer mill, because of its grate discharge, restricts discharge of oversize rock to the grate open¬ing, while at the same time providing a trap for removal of tramp iron or other uncrushables. The impactor discharges free, so generally works with a screen to control product sizes. The question of terminology, impactor vs, hammer mill, creates difficulties because the similarities appear to outweigh the differences by far; if one were to list the similarities in order of importance and then the differences, he would be forced to conclude that they would best be dealt with as a single kind of crusher. Taggart16 gave it four names and added "as it is variously known," but it must be remembered that in 1945 the machine was nearly exclusively of the flailing-hammer type, while today the fixed-hammer rotor is also com¬mon. In this chapter the terms impactor and hammer mill will be used where they seem to apply. It is perhaps unfortunate that this terminology is being confused with rock breaking at the mine, usually with hand-held tools, e.g., the article "High-Energy Impact Rockbreaking" by Grantmyre and Hawkes, CIM Bulletin, August 1975. General Description Impact breakers, impact crushers, and hammer mills accomplish material breaking and reduction primarily through impact action of the material with fixed or free-swinging hammers revolving about a central rotor. The material to be crushed enters through an opening at the top or top side known as the "feed opening" or "hopper opening" and falls into the path of rotation (hammer circle) of the hammers. Initial breakage is accomplished in midair by collision of the dropping feed material with high-speed hammers. The second stage of breakage occurs when the pieces hit plates or breaker bars which line the crusher boxlike frame. Hammer mills rely further on a shearing and attrition action between free-swinging hammers and grid bars or grates at the crusher bottom which restrict discharge of oversize material until it is broken sufficiently to pass through the grid opening. The term hammer is used in reference to the piece which strikes the material, whether it is fixed on the rotor or free-swinging. It

Jan 1, 1985

By N. K. Riddle

In many mines, it is typical to stockpile material for milling based either on analyses from exploration and blasthole drilling, or on the observation and judgment of experienced personnel. New analytical instruments make it possible to perform multiple, rapid analyses of as-mined samples at or near the mining face, so that sorting into stockpiles can be much more accurate. Using data and operating practices from a phosphate mine, a model was developed to simulate the function of analytical instruments in ore-grade control and ore stockpiling. With this model, it is possible to determine the recommended sampling points and sample frequency to obtain the desired confidence limits on the stockpile analyses.

Jan 1, 2003

By C. J. Bise

Virtual reality (VR) is a concept in which the human experience of perceiving and interacting with a computer-modeled environment is achieved through the use of sensors and effectors. It is an advanced form of computer graphics. The images are generated based on where the user looks and how the user moves. As personal-computer-based (PC) instruction gains acceptance as an innovative approach to providing safety training, VR can provide a multisensory, rather than merely a multimedia, mode of presentation. New technology continues to be introduced into the mining industry to meet the productivity needs of coal and noncoal producers. There is also an increased need for more innovative training of mine workers. New technology and equipment designs often affect the basic causes of accidents. For example, the development of cabs and canopies for underground coal-mine equipment has reduced the number of accidents related to roof falls and rib rolls. However, safety-training specialists then had to focus on the machines themselves, because the modifications had the potential for causing "pinch-point" accidents. In fact, although the overall physical demands on mine workers have diminished, there has been an escalation in the concerns about trauma from repetitive physical activity. Thus, health-and-safety training specialists have shifted their atten¬tion to the recognition, evaluation and control of workplace hazards (Hancock and Hill, 1995). Recognizing that the spatial relationships of a workplace convey more information about hazards when experienced rather than described, trainers agree that simulation is the method of choice. Unfortunately, until recently, simulation systems were either simple software programs that did not come close to portraying the real experience or were complex hardware systems (such as flight simulators) that did, but at a cost of millions of dollars (Fritz, 1991). However, researchers and training specialists are excited about an emerging approach to work-force education based on virtual reality. VR is also described as cyberspace, immersive simulation, artificial reality, telepresence, virtual environment or virtual world (Meyer and Dunn-Roberts, 1992; Peterson, 1992). It represents a group of concurrent advances in computer and interface technologies. They enable an individual to interact in a multisensory way with a computer-generated environment. To achieve this, a typical VR system incorporates a computer that contains the necessary databases for producing realistic images and audio; a head-mounted display (HMD) or screen for viewing the images; and a three-dimensional controller, joystick or data glove for interacting with the computer-generated environment. If virtual reality is to become an effective tool for the safety training of mine workers, its attributes will have to be measured against other forms of delivery. Accordingly, Carr (1992) listed the following areas in which VR should be considered the method of choice: ? When training mistakes would be costly. ? When the necessary environment cannot be experienced in the real world. ? To build interfaces that are sensible and can be manipulated. ? To make training situations really "real." ?To make perceptible the imperceptible.

Jan 1, 1997

By P. Maraboutis

Extractive industry (mining and quarrying operations), as other industrial activities, is subject to environment protection laws, regulation and standards such as the Environmental Impact Assessment directive, Natura 2000, Habitats & Birds directive, Water Framework directive etc The European Commission (EC) is aim to strengthen the EU environmental legislation to improve the (environmental and human) safety of mining activities. The mineral processing and the management of the mining waste will be covered by the new amendment of the Seveso II Directive, by a Best Available Techniques reference document (BREF) describing the Best Available Techniques of mining waste management and a new directive on the mining waste management. At the same time initiatives as the environmental liability, the energy taxation for environmental reasons and the natural resources management policy, which will have a positive impact on the protection of the environment, will affect the extractive industry operation procedures.

Jan 1, 2002

By O. Akinkugbe

The safe, productive exploitation of coal in multiple-seam situations requires specific design technology. At present, there are two general design approaches that the mining engineer can use to analyze the multiple-seam problem in question, either simple empirical relationships or complex numerical models. Often, the empirical approaches are too general for the specific problem and the numerical models require too much time and expertise for the practicing engineer. In this paper, a new program designed for quickly and easily calculating the stresses, strains, and safety factors associated with basic multiple-seam mining situations is presented. The program implements a simplified, two-dimensional boundary-element method in order to model the complex multiple-seam stress and displacement interactions. The program incorporates automatic coal and gob property generation to simplify the input, and inherently calculates pillar safety factors to enhance the output.

Jan 1, 2004

By Pedro E. Rengifo

Splicing methods have undergone considerable developments over the last 2Oyears. Continuous conveyor belt service is dependent entirely on the strength and life of the splice to hold the two ends together. Ultimately, belting performance is dependent on the quality, efficiency, and technique of the splicer. As customers demand better belting performance and running tensions increase, the need for splices that perform as efficiently as the belting has increased also. Higher dynamic belt constructions have also dictated the need for "new"sp1icing techniques. Regardless of the belt type used or spliced, one item that is most necessary with all belt types is the quality of the workmanship and standardized splicing methods that employ all of the necessary elements required to ensure reliable field service. This paper will explore the use of Goodyear-issued internal standards for field splicing following the constraints of quality and efficiency for fabric and steel cord reinforced belting. Also included are the 10 most common mistakes made by splicers, Goodyear-issued Field Quality Assurance Standards, and check lists for end users to adhere to the manufacturers' requirements for splicing including materials and specifications for conveyor belt splicing and repairs.

Jan 1, 2004

By M. Takayasu, J. Y. Hwang, F. J. Friedlaender, G. Kullerud

Al unite has been used as raw material for producing alumina and potassium sulfate fertilizer in Russia for many years. In the United States, this mineral has not been commercially processed though reserves of 5 to 10 billion tons of alunite ore have been estimated. Major constituents of these ores are quartz and alunite. The minerals are finely intergrown and liberation occurs below 10 µm. Adequate separation techniques for such ultrafine particles have not been developed. A new method for the beneficiation of al unite ore is proposed in this study. This method utilizes a small amount of fine magnetite upon which the liberated quartz is selectively flocculated. The co-flocculated magnetite and quartz are then separated from the alunite in a high gradient magnetic separator. Clean products, e.g., an al unite concentrate of 90% grade with 80% recovery, has been obtained from Utah ore. Techniques for selective co-flocculation of magnetite and quartz, separation of the carried quartz, and recovery of magnetite after separation are discussed.

Jan 1, 1987

By Ramon S. Pizarro, W. Joseph Schlitt

Introduction Trying to synthesize innovations occurring in gold processing is not simple. At present, this technology is exploding, brought about by the high price of gold. This price has compelled the mining industry, as a matter of survival, to produce gold. The frantic search for gold deposits continues, from glacial areas to tropical jungles. The search has been fruitful. New exploration techniques have helped to locate deposits. Some are amenable to conventional processing techniques. Others are in unusual settings that challenge the ingenuity of extractive metallurgists. Ore deposits containing traces of invisible gold, refractory mineralization, and impurities and deleterious materials that previously defied treatment are now being profitably processed. Metallurgists have developed various processing methods and equipment for gold ore treatment that reflect differences in ore characteristics, grade, mineralogy, reserves, topography, climate, and location. These processes can be categorized as: • For nonrefractory or readily leachable gold ores - vat leaching, heap leaching, and agitation leaching. • For ores containing free gold - gravity concentration methods, followed by mercury amalgamation, and • For refractory gold ores - flotation, roasting, pressure oxidation, followed by cyanidation leaching. In actual practice, a combination of these processes may be required. This is because gold mineralization, although usually simple, may be associated with other mineral species or with clays that make the ore difficult to treat. Furthermore, after the gold has been solubilized to form a cyanide complex, one of two important processes must be applied to recover the gold. These ore zinc cementation (Merrill-Crow process) and Carbon adsorption, desorption, and electrowinning. New techniques for leaching and recovery are also advancing. These will become the bases for the next generation of gold processing plants. Nonrefractory Gold Ores Nonrefractory ores with readily leachable gold are among the .easiest to treat. Even so, non-refractory ores from epithermal deposits are likely to contain too much clay. When these ores are damp, they may clog the screens and cone crushers. Depending on the type of process, scrubbing the crushed ore is very effective in overcoming clay problems. After dewatering, the slimes enter the cyanidation process and the thickener overflow is stripped of gold values and recycled. Semiautogenous (SAG) mills are also gaining popularity due to lower capital costs and ability to treat wet, sticky ores. If properly sized, the secondary crushing and screening plants, together with a secondary ball mill, can be eliminated. When the ore is of such a low grade that it can not support fine grinding, vat or heap 'teaching may be applicable. These systems are being actively applied in the US and elsewhere. Rapid construction and low capital costs are important features of these plants. Vat leaching is ideally suited for fast leaching ores and small tonnage deposits located in areas with harsh winters or wet tropical climates. For effective vat leaching, the ore is crushed to less than 25 mm (1 in.), agglomerated with lime or cement to control fines, and leached with sodium cyanide solution (upflow or downflow). The degree of size reduction is a tradeoff between increased costs of comminution and improved gold recovery from smaller particles. However, the size of material

Jan 11, 1984

By W. H. Jay, F. Lawson, D. F. A. Koch

Ion exchange resins may in the future displace activated carbon in gold plants where cyanidation is practiced. Recently patented technology based on interpenetrated polyurethane polymers shows that these new materials offer significantly improved loading kinetics over both activated carbon and commercially available ion exchange resins. These polymers are not restricted either in particle size or in density and therefore offer the gold industry the potential for a further technological advancement.

Jan 1, 1995

By Larry A. Lien

Membrane technology has been available for about 30 years, but has been used very sparingly within the general mining industry. However, recent developments in polymer chemistry, spiral wound element construction, pretreatment equipment and element cleaning techniques have improved the reliability and robustness of membrane based systems. These improvements have expanded the potential to use this "new" technology to enhance critical recoveries of gold and silver in heap leaching operations or in the extraction circuit. Another opportunity for the mining industry will be to use membrane technology in new processes like controlling organic acids or ammonium thiosul­fate to enhance gold and silver extraction during leaching opera­tions. Finally, the most common use for membrane technology is for the control of mining water balance and acid mine drainage issues. Polymeric membranes, specifically thin-film composites, have been developed that will purify, fractionate or concentrate gold or silver. Recent applications have been developed for spi­ral wound modules that operate across the pH spectrum from 0 to 14. Systems using membranes have been constructed that operated on feed streams from 200° C to 3000 centipoise. Most recently, membrane based systems have been pilot tested suc­cessfully to purify solvents, like LIX. Opportunities exist to apply membrane technology to concen­trate gold and silver cyanide solutions with thin-film composite Reverse Osmosis (RO) membranes at elevated pH values above 10. Incorporating membrane technology could allow one to increase production without incurring additional expansion of the gold extraction side of the process. Furthermore, free cyanide is not rejected by the Reverse Osmosis membranes, but other inorganic salts are rejected 98+%, thereby, allowing an essentially ion free, except for the free cyanide, to be recirculat­ed back to the heap leach operation for enhanced extraction.

Jan 1, 1998

Fine coal is substantially more costly to process than coarse coal because of technical difficulties associated with separating fine particles and removing process water from both clean coal and refuse. Therefore, companies are often forced to discard coal fines to waste impoundments. According to a recent report published by National Research Council, the U.S. coal industry is discarding 70-90 million tons of coal fines annually to 713 active impoundments, most of which are located in Central Appalachia. On October 11, 2000, a 72-acre impoundment near Inez, Kentucky, accidentally released 250 million gallons of coal slurry into nearby underground mines, creeks, rivers, and schoolyards, thereby creating serious environ-mental concerns. Fortunately, recent advances in separation technologies make it possible to recover fine coal more efficiently from existing coal preparation plants and from waste streams previously discarded to impoundments. The availability of these new technologies allows companies to increase profitability and minimize environmental risks, which are conducive for achieving sustainable mining.

Jan 1, 2003

By Gerhard Mücke

Geothermal and operational reasons in the German coal mining industry make it necessary to an increasing extent to climatize coal faces and headings by means of refrigeration plants. Air coolers installed on coal faces as well as in gateroads play an important part in such climatization. They must transfer, under difficult conditions, the refrigerating capacity supplied by central or de-central refrigeration plants from the chilled water to the air in the workings. The performance data of two new types of coalface coolers and of two different types of gateroad coolers were measured in two testing stations under different thermo- dynamic conditions with dust-free fresh air. As air coolers must be installed particularly at working points with a high .dust load the heat exchanging surfaces are fouled for the most part causing an essential reduction of the refrigerating capacity. The investigations therefore were extended to measurements with a certain dust load in the intake air of the coolers.

Jan 1, 1980

By Kal V. S. Sastry

Mineral processing simulation has come a long way since its beginning about thirty years ago. With our increased understanding of mineral process systems and the advent of new software and hardware technologies, we can visualize an ideal mineral processing simulator. This paper attempts to identify a number of desirable features of an ideal mineral process simulator and to describe the exciting trends in making such an ideal simulator a reality.

Jan 1, 1992

By S. D. Bechtel

Bechtel Civil and Minerals, Inc., one of the Bechtel group of companies, is a large engineering and construction firm that services the mining industry, among others. The firm's head, S. D. Bechtel Jr., comments on how his E&C company is dealing with the recessionary economy. First, he offered a historical perspective. About a half century ago-in the middle of the Great Depression-W. A. Bechtel and several business partners drew up a fixed price bid to build the Hoover Dam. At that moment in history, the W. A. Bechtel Co. was a modest success, but the times were troubled and uncertain. Money was scarce and a lot of contractors across the country were one project ahead of bankruptcy. The bid for Hoover was a make-or-break proposition for Bechtel, and it turned out successfully. The Hoover Dam was a no-frills operation in an isolated and harsh environment. There was plenty of hard work, long hours, and not many amenities. Controlling costs was critical. Everyone knew what had to be done, and why and what the consequences were. Today's Challenge Bechtel is now a bigger, more complex organization whose management views the current economic recession as a challenge to be met in much the same way W. A. Bechtel met the challenge of the Hoover Dam: by pulling together with a sense of purpose and direction. In many respects, Bechtel's situation today has a number of parallels to that which faced my grandfather. The company is eminently successful, but times are tough and there are plenty of signs that they could get tougher. My grandfather bet on the Hoover Dam to insure the future health of his company and I think we can work together again in that same tradition, make some tough decisions together, and the company's future can be just as promising. The first and most important requirement is to make certain that everyone understands the situation. The Bechtel group of companies are in an excellent financial position now. Its workload hit an alltime high in 1982 and it is well positioned in its principal markets. But the next two years may be critical for the company. Traditionally, Bechtel's work load lags behind general developments in the economy. Although many of its clients continue to suffer serious business difficulties, Bechtel is only beginning to feel the impact. The worldwide market for basic metals remains soft; relatively low prices and abundant supplies of oil and gas have flattened the petroleum market and made once promising synfuels projects economically unattractive; utility clients are still caught in the vise between overregulation and escalating costs. And persistently high, long-term interest rates have made capital investments expensive and difficult to justify. The company maintained a healthy workload through 1982. In some areas it has had little new work and consequently has been forced to lay off some staff as projects have been canceled or concluded. In other areas new work has tided the company over and more people have been hired. But new work bookings have fallen off, creating some uncertainty for the near future. 1983 requirements are clear, although seemingly contradictory. Belt tightening and cost reduction are necessary for Bechtel to remain healthy and competitive, enabling it to handle a possible further downturn with a minimum of turmoil and dislocation. At the same time, we need to allocate resources and funds in areas that will keep us positioned for the turn-around marketplace.

Jan 2, 1983

By Ian Corrans, Gary Johnson, John Angove

The Activox™ process is a new method for the pre­treatment of refractory gold ore concentrates prior to cyanidation. The process has been developed in Western Australia, and relies on a combination of fine grinding and pressure oxidation to achieve the destruction of sulphide minerals and the liberation of encapsulated gold. The process operates under much more moderate conditions than those that would typically be used for conventional pressure oxidation of similar concentrates. This results in significantly lower capital and operating costs being achievable.

Jan 1, 1993

By Ahmed A. El-Saie

To reduce the problem of overbreak and its associated added costs, a new technique is proposed to make a slot around the tunnel profile in hard rock. The Finite Element Method was used to investigate the effect of the slot on the stress field and deflection of the tunnel core. Beam theory was also applied to calculate the stresses and deflections of a slotted tunnel for several different slot depths.

Jan 1, 1981

By Thomas Oberndorfer

Recent publications indicate that there is a rising interest in the field of mining method selection, and increasing efforts are being undertaken to develop satisfying solutions. Yet, computer assistance for mining method selection (MMS), or in other, terms assistance in the (pre-)feasibility state of a project, still lags behind the computer application in other mining activities. This is true for research as well as for application. This paper is intended as a contribution to the development in computer-assisted mining method selection, and focuses especially on underground hard-rock mining. It is structured in four main parts. The first deals with general aspects of mining method. selection within the process of mine planning, and with problems and requirements which derive from this specific situation. In the second part some numerical MMS-approaches hitherto published are briefly introduced, and investigations on these approaches are discussed. Based on .these experiences, in the third part an analysis of the complex system MMS is presented. It focuses on heuristics, influencing factors, objectives, assessment-routines and mining methods, and emphasizes the essential necessity of a profound mining method description (MMD) specially developed for the requirements of MMS and numerical processing. Accordingly the fourth part of this paper presents a mining method description model developed at the Department of Mining Engineering, Montan-University Leoben (MUL), Austria. It describes the consequences of the investigation, in particular the new mining method description model, on 'the design of a MMS-system. The paper closes with a outlook on the possibilities of an successful MMS-system being realised.

Jan 1, 1992

By C. R. Tatman

Failure to achieve the planned production rate at new mines and mine expansions has a major adverse impact on a project's economics. A study of 60 steeply dipping tabular deposit-type underground mines showed that 35% of the mines did not achieve their production goals. An empirical formula based on the geometry of the deposit and expressed as a rate factor is applicable to select a production rate for this type of deposit. The formula is: Annual production rate = Rate factor x Rate multiplier. The appropriate rate multiplier for each category of deposit thickness and the associated risk can be used to select an appropriate production rate.

Jan 1, 2002

By Sara J. Heinlein, George Malkos, James E. Lindell, Tony Pestonatto

The 79th Street Water Tunnel Extension Project was initially designed by the City of Chicago, Department of Public Works, to increase the capacity of the City’s south side water distribution system. MWH preformed a design review, prepared the final design and provided construction management for the City of Chicago Department of Water. Construction commenced in September 1995 and was completed in October 1999. The Project connected two existing water tunnels with a new 5.8 km (19,044 ft.) long, 4.9 m (16.08 ft.) finished diameter concrete lined rock tunnel utilizing TBM, drill-blast and mechanical hoe-ramming methods. In addition, approximately 61 meters(200 feet) of concrete lined variable cross section tunnel, a new gate shaft and a temporary construction shaft were constructed. This paper describes the construction of these features and the geological conditions encountered.

Jan 1, 2003