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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 William Mayrsohn

IMTRODUCTION The marketing aspects of a new precious metals property is often not considered until the mine actually begins production. At this point in time it is often too late or too expensive to change the mine's final product and not enough time to do an effective marketing program. MINE PRODUCT The rule for determining the mine's final product: The higher the gold and silver content, the greater return of metal at the lowest post-mining cost. . Dore Bullion: Most advantageous Advantages: - Highest return of metal. - Lowest refining cost per ounce of gold and silver. - Very compact and easy to ship in small quantities. - Easy to assay. - Assays between mine and refiner are comparable. - Melt losses are very small at the refiner. - Outturn of gold and silver 20-30 days for quick cash flow. - Gold/silver refiners can return or purchase metal soon after arrival at a nominal financing cost.

Jan 1, 1987

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 D. Jacobson

There are many different machine design parameters and variables that affect the production of cone crushers in a mineral processing plant. One of these variables is the speed at which the cone gyrates. In June 2012, pilot tests were conducted to determine the production and operating conditions over a wide spectrum of speeds. mining operations will have variations in the ore characteristics and feed rates that result in non optimal use of the crushing energy and inconsistent process control. This study documents the measured variation in production and energy efficiency with two operating modes. Overall, the results match the theory, and the capacity and power fluctuated by 25% and 17%, respectively, when operated at full capacity, with an overall trend of slightly coarser discharge size distribution as the speed decreased. Using a fixed feed rate, the crushers had 4-14% higher production when operating at the optimal speed. Secondary analysis showed that the power draw consistency and magnitude of power spikes could also be improved by optimizing the cone speed. Varying the speed of the crusher can be used to tune the crusher during commissioning, adapt to changing ore conditions over long periods of time or be used as a dynamic input into an advanced control system. each action above would serve to make the crusher(s) more productive, more energy efficient, impove process control and would also have mechanical benefits for the machine

Dec 1, 2013

By A. T. Yu

Two major events highlight recent developments in US ore and coal ports: completion of the last series of modern taconite pellet transshipment facilities on the Great Lakes; and modernization and construction of coal ports, particularly on the East and Gulf Coasts. The New Taconite Transportation System To reduce raw material transportation costs, a fleet of new generation high-capacity 304-m (1,000-ft) self-unloading vessels were built to carry iron ore pellets from the Minnesota-Michigan iron ranges to the steel plants on the lower Great Lakes. Existing port facilities had to be modernized, revised, or completely rebuilt to accommodate these large vessels. Some of these were Burlington Northern's Allouez, WI, loading dock; Duluth, Missabe & Iron Range Railway Co.'s Two Harbors, MN, facility; Republic Steel's Lorain, OH, facility; and Chessie's Toledo, OH, dock. Allouez and Two Harbors receive taconite pellets from unit trains and load them onto large vessels either after dumping or via a large stockpile and reclaim system. The Lorain facility receives iron ore pellets from self-unloading vessels' discharge boom conveyor and reloads the pellets into rail cars or small vessels destined to inland steel mills. The Toledo facility receives Armco pellets from vessels, stockpiles them through the winter, and reloads into unit trains destined for Armco's mills along Chessie's rail tracks. Burlington Northern's $75-million Allouez pellet dock, completed in June 1977, was built to receive pellets produced by Hibbing Taconite Co. and National Pellet Plant in Minnesota, stockpile them through the winter when the lakes are frozen, and load them into 304-m (1,000-ft) vessels in the shipping season. As much as 10 Mt (11 million st) of pellets may be stockpiled within the loop track. A 6-km (4-mile) long conveyor system connects the stockpile area and the dock. Thirty-six new concrete silos were built on the dock to house 2 kt (2,000 st) each of pellets before shiploading. The $35.5-million expansion of the Two Harbors transshipment facilities began shiploading in July 1978 after ground breaking in Aug. 1974. Particularly noteworthy is the first application of the Orboom system-a breakthrough in technology for the modernization of the century-old pocket docks on the Great Lakes to accommodate the new generation of super vessels. The pocket-type loading dock has been a standard on the lakes for nearly a hundred years. Bottom-dump rail cars fill the ore pockets on top of a finger pier. Gravity chutes matching standardized ore ship hatch spacings are lowered to fill the holds of a 20.3-kt (20,000-dwt) ship. The construction is simple and the loading swift. In spite of advances in technology elsewhere, most of these docks continue to serve the iron ore and coal trade in the same manner they did in the 19th century. Although performance of the pocket docks on small vessels remains outstanding, the new 304-m (1,000-ft) vessels are beyond the reach of the old docks. After extensive development, the Orboom system (Patent No. 4,065,002) for pocket docks was successfully developed. The heart of the Orboom system is the retractable shuttle loading arm which loads the wide beam vessels. The Orboom shuttles are fed by existing pockets of the dock that, in turn, are charged by a tripper conveyor along the length of the dock. The Two Harbors shiploading system is supported by a 0.9 Mt (1 million st) storage-reclaim network. Unit trains are bottom dumped. Taconite pellets are stacked and reclaimed by bucket wheel reclaiming systems. Lower Lakes New Ore Ports At the lower Great Lakes receiv-

Jan 10, 1982

By L. Stas

The authors have been interested in stress measurements in the rock mass for a long time. This paper describes the development of new apparatus for stress measurements in a rock mass. The principle of stress measurement by this device is based on the relief method as applied on the conical shaped surface of the bottom of a borehole. The design started based on the experience of K. Sugawara and Y. Obara who have been using the compact conical borehole over-coring system (CCBO). The conical shape of the strain gauge probe CCBO makes the fixation of the probe in borehole easy and, also, makes the measurement of stress in independent directions possible. The principle of the measuring method, the preparation of the borehole, the design of the probe for continuous measurement of stress during the course of overcoring are described. Also, a simplified version of the probe for long term monitoring of stress variations in the rock mass by means of the inserted body method and the initial laboratory results and in-situ testing of the development sample are described. Additionally, testing was done regarding the possible glues in relationship to the creep effect for this case.

Jan 1, 2006

By Patrick McElhinney, Jacob Carr, Bruce Whisner, Cory DeGennaro, Jingcheng Li

Since 2016, electromagnetic interference (EMI) of personal dust monitors (PDMs) with magnetic proximity detection systems (PDSs) has been observed in underground coal mines. The EMI causes the magnetic field measurements of a PDS to change, which, in turn, alters the calculated location of the miner relative to the machine. Any altered location calculation can potentially cause the PDS to fail to warn a worker who is at an unsafe distance from the machine, arousing a serious concern on safety hazard caused by EMI in underground mines. The search for EMI mitigation strategies led to the development and use of large shielding pouches and boxes to hold the entire PDM to reduce its magnetic emission. Research on these pouches and boxes found that although they were able to reduce the emitted radiation from the PDM, they also disturbed the magnetic field of the PDS, affecting its performance. Researchers from the National Institute for Occupational Safety and Health (NIOSH) have focused on shielding internal PDM components rather than shielding the entire PDM. The PDM air pump motor is one of the PDM components that has been identified as a major source of electromagnetic radiation and has been selected for further study and tests. The measurements show that a small copper or aluminum foil enclosure can effectively reduce the magnetic emission of the motor by between 50 and 85% at 73 kHz. This study compares the test results of the air pump motor with various cost-effective shielding materials. The data provided in this paper can serve as a reference for shielding enclosure design of the PDM air pump motor to reduce its electromagnetic emission as one form of EMI mitigation strategy.

By E. M. Frizzell

In an effort to economically and efficiently enhance the erosion control aspects of present surface coal mine reclamation practices, the US Bureau of Mines has recently completed a two-phase research program wherein irrigation strategies and equipment developed under the first phase were field tested on three surface coal mine sites. The fundamental basis for the use of irrigation as a reclamation tool is to provide the plant moisture requirements as a supplement to prevailing natural precipitation, and thereby support the natural growth of drought-hardy native vegetation. Portable solid-set irrigation equipment and several irrigation strategies were tested on large 6-ha (15-acre) sites in Montana, Wyoming, and New Mexico. Results of these tests will be presented which include daily irrigations, precipitation levels, soil moistures, climatic data, and density cover and biomass of the native plants.

Jan 1, 1987

By Gary Beerkircher

WaterFlush Technology and WaterFlush crushing offers significant operational ben­efits in gold milling operations. WaterFlush crushing is the technology that Nordberg Inc. has developed, tested and proven in an actual operation during the 1980's. Patents have been obtained for both the process and the apparatus of implementa­tion. WaterFlush involves volumetric process controlled water flow into the ore feed cav­ity of a WF cone crusher. While the addition of water in itself is not new, the con­trolled amount of water coupled with the WF crusher operating parameters are revolution­ary. The WF crusher is a specially designed version of Nordberg's Omnicone crusher oper­ating at higher speeds, with a reduced ec­centric throw and higher horsepower capabil­ity. The results are increased capacity, higher crushing energy input and a finer crusher product. The WF crusher product is a slurry containing 40-60% solids by weight.

Jan 1, 1990

By Huaiyu Liu, Shan Liu, Dashang Chang, Maixi Lu, Yaqun He, Yali Kuang

The expert system for coal preparation plant design mainly solves the crux--separation flowsheet design and optimization of product structure. There are twelve basic flowsheets available in the system which are representative of financial plants. The system can select better flowsheets automatically according to the property of feed and scale of plant. Then, it can choose the best flowsheet and product model from the better flowsheets through analysis and optimum calculation. The expert system is made up in Turbo Pascal 6.0 and consists of three sub-systems: Lump and grain coal system, coal slimes processing system, and raw coal system. Several representation methods, such as production rule, procedure, and object-oriented programming, are used to express the expert's knowledge in the system. To decide the optimum product structure, Zangwill's method is used to make an advance product model. The expert system has the performance of interpretation strategy, by 'tracer" technology and pre-arrangement text, and of learning new expert's knowledge.

Jan 1, 1996

By Martin P. Schroeder

"Challenges have emerged as subway systems age and as new tunnels are bored in congested corridors or in high-risk environments. To help public transportation agencies address tunneling challenges, the American Public Transportation Association has convened numerous independent industry peer reviews composed of top experts in their fields to come together and provide recommendations and solutions. This paper provides case histories of peer reviews that include topics such as boring through toxic soils, boring underneath existing tunnels, retrofit of tunnel ventilation systems, and mitigation of water intrusion. Peer reviews are applicable to all tunnel projects worldwide. The paper will highlight the conditions of these challenges, peer review recommendations, steps taken to reach agreement, and the successes that resulted, which led to major changes, new legislation and reduction of risk. INTRODUCTION Public transit agencies face many challenges in maintaining and expanding safe transit operations, especially as systems age, ridership expands, and budgets remain flat. The development of new industry standards and federal safety regulations places further demands on transit systems, with compliance often taxing in-house resources. Studies of the state-of-good-repair across US public transit systems indicate a current backlog of $84 billion in maintenance projects, which will require an investment of $18.2 billion per year to eliminate the backlog by 2030[1]. Systems not in a state-of-good-repair may not operate efficiently, may not be available to meet the growing ridership demands, and may not meet required safety goals or reduction of risk. Innovation is another clear need transit agencies have for improving system performance and lowering operating costs.To meet these challenges, transit agencies often turn to industry peer reviews for guidance and recommendations as part of their overall strategy to maintain and grow the safe operation of their systems. As a service to its members, the American Public Transportation System (APTA) has developed an industry peer review program designed to give agencies opportunities to learn from each other and help them address challenges in operations, engineering design, and construction of their systems. Over the past 20 years, APTA has performed hundreds of peer reviews covering all aspects of transit system operations from fare collection to agency organization, project delivery methods to safety culture, and engineering design including tunneling and tunnel fire ventilation. As rail transit systems expand to meet increased ridership, it is often necessary to bore new tunnels for alignments in congested areas where surface rights-of-way are lacking. Such proposed alignments can pose significant challenges for transit agencies, as they contend with various tunneling problems."

Jan 1, 2016

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 R. Pakalnis

A comprehensive project has been completed at the University of British Columbia that focused on the development of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. The project began in 1989 under the sponsorship of HDRK Ltd., a consortium of mining companies including Inco, Noranda and Falconbridge Ltd. The objective was to develop a cuttable cable bolt that would serve as support for a continuous miner within a hardrock environment (Mah, 1994). The bolt was required to be cuttable by a continuous roadheader without adverse effects to equipment, personnel and the milling process. From the beginning, the focus was to employ existing cable bolt installation technology (Goris et al., 1994) whereby the cable bolts are grouted within a 4.8-cm-diam (1.08-in.diam) or larger employing a portland cement grout having a water:cement ratio between 0.35:1 to 0.4:1.

Jan 1, 1994

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 M. Dosemeci, M. McCawley, J. McLaughlin, Z. Wu, F. Hearl, W. Blot, K. Peng

Proposals have been made by two organizations, the International Standards Organization (150) and the American Conference of Governmental Industrial Hygienists (ACGIH) for a revised respirable dust criteria and criteria for thoracic and inspirable dust. These criteria yield different results than criteria based on lung deposition patterns in assessing the hazards due to dust exposure. Since these differences are a function of the size distribution of the dust an analysis of dust size distributions from various mining operations was performed to determine the amount of difference that could occur. The dust size distributions available for this analysis were taken from U.S. coal mines and from Chinese metal mines. The mass of mechanically generated dust that will deposit in the alveoli was found to be in direct proportion to the ISO/ACGIH criteria estimates in the mines studied. Therefore, respirable dust estimates for substances such as coal and silica are not a problem. Estimates of exposure to diesel exhaust in these mines, however, were not always in the same proportion to the estimated alveolar deposition. Also, concern with an excess of bronchitis among miners may not be adequately addressed by the use of samplers conforming to the ISO and ACGIH criteria. The cascade impactors used to acquire the data for this analysis require four to eight substrates per sampler. For daily dust exposure assessment this method is cumbersome and time consuming. Therefore, two new samplers have been designed to meet the need for determination of deposited dust mass. These samplers follow the lung deposition curve rather than the penetration curves proposed by the ACGIH and ISO and require analysis of only two substrates per sample.

Jan 1, 1992

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 John J. Gillis

There is an ongoing battle to gain general acceptance of fossil fuel byproducts as safe, economical and useful agro-industrial materials. Despite that, the US ash industry is witnessing a steady growth in the volume of coal burned, along with the production of greatly refined, higher-quality ash particulates. There are two principal reasons for this. Economics have caused an increasing number of US electric utilities to convert from oil-burning to coal-burning. And the Federal government has tightened specifications on fly/bottom ash production quality. Hence, it must be noted that new and more stringent Federal regulations were implemented in 1980. The resultant ash particulates are finer, more compact, and less heavy than in previous years. Additionally, the first shift from oil to coal in the US was initiated in December, 1979 by the New England Power Co. in Massachusetts. Coal is the most widely-distributed fuel in the US. And it is found in 38 states. The wide availability of this fossil fuel and its general cost-efficiency, coupled with the undaunted move of US electric utilities toward nuclear power, are major factors affecting the current statistics on ash generation (65.4 x 106 million tons). Interest in the use of coal in power plants is creating a unique ash disposal and use situation for ash producers as well as the Federal government. There are growing quantities of fly/bottom ash residue. Ash producers must decide how this byproduct can be dealt with effectively and profitably. At the same time, government agencies such as the US Environmental Protection Agency (EPA), are commissioned by Congress to assure that solid, liquid, or gaseous material released into the environment is not harmful or offensive to human health and the environment. Additionally, the Federal government is often responsible for establishing and enforcing guidelines and standards governing the use of recycled materials. Several standards and guidelines governing the properties and use of ash in the US have been established by governmental agencies as well as by the ash industry itself. Of these, some have been developed for ash use by a specific federal agency. Others apply to the entire industry. The following is a brief identification of the major specifications for fossil fuel ash: • US Corps of Engineers - These specifications were first established in 1957. They delineate the physical and chemical requirement for pozzolans used in mass concrete. These specifications applied only to Corps of Engineers' concrete construction projects for locks, dams, and other mass concrete projects until 1977. At that time, a joint effort between the American Society for Testing and Materials and the Federal government produced a modified specification that is now generally applied. The Corps of Engineers' ash, however, retained certain aspects of its specifications for its own use, particularly in the area of handling and shipping fly ash to its own projects. Prior to transporting the fly ash to the corps, all potential sources for the ash must be inspected and approved as a supply source. All silos must be filled, sealed, and tested before the ash is released for shipment. The normal test period for the ash is seven days, although several testings may require up to 28 days. Once the fly ash has been released, it can only be shipped to US Corps of Engineers' projects. All shipments are made with a government inspector present during loading. After a truck or railcar is loaded, the silo is resealed until the next shipment. This procedure requires three silos, and a minimum of 454 t (500 st) each should be considered for each storage unit. All silos are strictly committed to Corps of Engineers' use and are not available for other commercial shipments. • US Bureau of Standards - This Federal agency maintains a standard testing sample of nearly every product used in the US. The accuracy of the fly ash chemical analysis is measured by a regular cement and concrete reference laboratory (CCRL) inspection and based on test results from a standard sample of cement. • US Bureau of Reclamation - This agency pioneered several projects using fly ash and required Federal Standard Certification for pozzolans. • American Society for Testing and Materials (ASTM) - This nongovernmental organization began preparing standards for fly ash sold and used in the cement and concrete industry in 1947, at the urging of ash marketing firms. Current standards define chemical and physical requirements and is entitled, "Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete (C 618-80)." • State Highway Specifications - Led by Alabama, many states are moving toward permitting - and in some cases requiring-the use of fly ash in portland cement concrete and with lime for base stabilization projects for roads and highways. • Federal Aviation Administration (FAA) - The FAA acts in an advisory capacity. It has final approval on design specifications for airport construction projects. The agency has established a set of guidelines permitting the use of fly ash, and has approved several fly-ash-specific designs. The most current FAA fly ash projects

Jan 8, 1984

By S. O. Yuan, R. L. Grayson

As a followup to a USBM-sponsored research project, the authors utilized the knowledge-base structure and system concepts from a Sun Sparcstation-based worker-scheduling system of the mine-management support system to develop a PC-based application. The new software adopts the nested-window concept to facilitate data collection and modification on personnel, including their availability and work priorities during a shift. The system can optimally allocate manpower on a work shift and can delineate supervisory training responsibilities. The various components of the software, including enhancements made to the original system, are described in detail.

Jan 1, 1998

By Z. Sample, S. Kaushik

"INTRODUCTION Industries around the globe have been making significant advancements in recent years due to innovations in automation technology. With the implementation of modern automation technology, professionals in process automation or plant operations can expect significant and exciting change, and the mining and mineral processing industries are no exception. From 2000 to 2010, the International Council on Mining & Metals (ICMM) reported that an increased output and increased value of most metals has resulted in a rise in global metal and mineral process industries from $214 billion to $644 billion. [1] Since most productivity increases in mining and mineral process industries have been achieved through the ability to process lower grade ores with improved efficiency and larger equipment, these industries have begun to adopt advanced automation and control technologies. Despite a growth slow-down, the mining and mineral processing industries are poised for continued and sustainable growth and development due to an increasing demand for energy minerals and emerging technologies requiring minerals and metals previously not demand. However, as these industries becomes more automated, new challenges are arising on the horizon. DEMOGRAPHIC TIME BOMB John Payne from BP is credited with first using the term Demographic Time Bomb to describe the upcoming crisis in the process industry in finding experienced operations personnel. From a survey of 912 mining professionals, Stratum International found that a mere 0.4% of senior level candidates were between the ages of 25 and 34 and a similar proportion aged over 75 years. This indicates that there is both a deficiency of young skilled workers and a skilled workforce that is retiring earlier than the previous generation. Combined with data published by the US Department of Labor stating that the median age of the mining workforce is approaching 50 years old, this implies that these skilled mining and mineral process professionals are an aging population with irreplaceable knowledge and experience that are expected to retire in the next 5-10 years. While it is projected that the labor pool will be sufficient to fill open positions, the real question is if this young workforce will have necessary skill sets and experiences."

Jan 1, 2015

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