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By Wojciech Klecan

Cobb County, located on the northwest side of Atlanta, GA, is continually growing and, like many other metropolitan areas, it needs to increase the capacity of its waste water system to meet future demand. The Cobb County Water System (CCWS) is the responsible agency for water distribution, waste water collection and treatment in most areas of the county. CCWS, one of the most progressive agencies in the metro-Atlanta area, is addressing its future waste water capacity needs in the southern part of the county with the construction of the South Cobb Tunnel and Pump Station. This project consists of an 8.8-km- (5.5-mile-) long, 8.2-m- (27-ft-) diameter, tunnel boring machine (TBM) excavated waste water storage and conveyance tunnel; six tangential vortex-flow intakes ranging from 1,533 to 5,700 L/s (35 to 130 mgd) peak flow capacity, two construction shafts, six 1.8-m (6-ft) finished diameter connecting tunnels ranging in length from 6 to 975 m (20 to 3,200 ft) and a 5,700-L/s (130-mgd) wet/dry pit pump station. The pump station will have a semi-circular wet well with a dividing wall that extends almost to the top of the shaft and a spilt dry well for reliable operation. Roller gates will control the flow to the wet well from the tunnel. The pump station will have six 1,420 L/s (32.5 mgd) pumps and two sets of stair wells and elevators. With a finished diameter of 32 m (104 ft) and a depth of 62 m (204 ft), this is the largest pump station shaft constructed so far in Georgia for the dewatering of a waste water tunnel. The pump station shaft was also the highlight of the well attended and successful 2009 Shaft Design and Construction Short Course held in Atlanta, Sept. 10-11. The two-day course was sponsored by the Underground Construction Association of SME and Pennsylvania State University and concluded with a field trip to the pump station shaft. The tunnel starts south of the city of Austell and finishes at the South Cobb Water Reclamation Facility (WRF), located on the banks of the [ ] Chattahoochee River just north of Interstate 20 (Fig. 1). The South Cobb Tunnel will run 30 to 137 m (100 to 450 ft) below the surface, with an average depth of about 91 m (300 ft), through metamorphic rocks (Fig 2). The construction contract was awarded to Shea-Traylor JV with the lowest bid price of $305 million and notice-to-proceed was given on July 14, 2008. Jordan Jones & Goulding, Inc. (JJG) is the project designer and performed the geotechnical investigations. Parsons/Jacobs Associates is the construction manager. The South Cobb Tunnel is CCWS?s second deep hard rock tunnel. The 15.3-km- (9.5-mile-) long, 5.5-m- (18-ft-) diameter TBM excavated the Chattahoochee Tunnel was the first deep tunnel to be construced in Cobb County. Construction began in 2000 and the project was completed four years later. It is located about 16 km (10 miles) northeast of the South Cobb Tunnel in similar geology. It was designed by JJG to meet east Cobb?s long-term waste water capacity needs and provide flow equalization to the R.L. Sutton WRF. The Chattahoochee Tunnel was named ?Outstanding Civil Engineering Project of the Year? by the Georgia Sec-tion of the American Society of Civil Engineers in 2006.

Jan 1, 2009

By D. Newman

Multiple seam mining is prevalent in Southern Appalachia because economically mineable coal seams are numerous and frequently occur in close vertical proximity. West Virginia, Kentucky, and Virginia have 117, 55, and 40 mineable coal seams respectively. It is extremely rare to have an underground mine that has not been undermined, overmined, or has mining adjacent to it. In many cases the multiple seam mining is concurrent with extraction sequenced in superjacent seams. Because underground mining is focused on recovering the most valuable reserves, mining is rarely practiced from the top seam down, which is the practice most conducive to stability. The combination of room-and-pillar mining methods that include development only, small block, partial retreat, full retreat, and longwall mining produce a wide range of mining geometries and complexity in underlying and overlying seams. In the future, the number of multiple seam operations will increase as reserves are depleted and future mines are, by default, located closer to abandoned mine workings. The improved coal market has transformed many formerally uneconomically mineable seams into attractive reserves. The approaches and methodologies used for multiple seam stability analysis are dictated by the site conditions, including overburden/interburden thickness and lithology, mining geometry, and the mining methods in both the active and abandoned mines. Multiple seam stability analysis using analytical and numerical methods is illustrated by two case histories that reflect close proximity room-and-pillar mining and mining in bump prone situations.

Jan 1, 2007

Underground mine designs typically try to avoid extraction beneath streams and rivers of any significant size, especially when the overburden rock thickness between the stream bed and the mine is thin. Potential issues with mining beneath streams include excessive groundwater inflow to the mine; weak ground (roof, floor, and pillar) conditions; horizontal stress effects; as well as stream loss and other potential adverse environmental effects. However, there are times when crossing beneath a stream or river is necessary to move into a new area of mineral reserve without creating additional mine access points from the ground surface. Often, stream crossings are completed without thorough assessment, potentially resulting in increased costs, decreased safety, and, in some cases, failure to advance the mine. Selection of the most favorable location(s) to cross the stream must account for numerous factors and the associated assessment often requires a multidisciplinary approach. Stream crossing investigations often require geological, hydrogeological, geotechnical, and geophysical expertise. Phases of stream crossing investigations include desktop evaluation of maps and aerial photography, stream bed observations, drilling, detailed rock core logging, downhole geophysical surveying, hydraulic conductivity testing (packer testing), geotechnical laboratory testing, assessment, and reporting. The deliverables from a stream crossing assessment typically include geological, geotechnical, and hydrogeological characterization of potential stream crossing locations; classification of favorable and unfavorable crossing locations; recommendations for entry design and pillar sizing; and recommendations for if, and how, to conduct pre-grouting activities. Examples of technical aspects of data collection and assessment are provided based on decades of industry experience conducting stream crossing assessments in various underground mining scenarios.

Jul 28, 2020

By Richard R. Klimpel

During the last 28 years, I have had the very challenging and rewarding experience of working as an engineering professional in a large multinational company, both as a manager of engineers and engineering projects as well as an inventor and generator of new engineering processes and products. Due to the diversified geographic and tech¬nical nature of my employer's business, my responsibilities have taken me all over the world. This has included interactions with people in different industries including minerals, coal, chemicals, petroleum, pulp and paper, agriculture and pharmaceuticals. As diverse as my experience may seem, it has always amazed me how common the basic underlying technology and economic trends are that shape the working environment that any given engineer in any given geographic loca¬tion will experience. I would like to discuss the industrial evolution from micro to macro engineering. One of the basic truths behind how industry must and will operate is "change," including: • the creation of conditions for change, • the anticipation of change, • the resistance to change, • the rewards that being part of a change can bring and • the destruction that change can bring to the unprepared. This fact was well stated by Heractitus around 500 BC.: "There is nothing permanent except change." This simple truth has been valid since the dawn of time and, if anything, is accelerating in nature every decade.

Jan 1, 1993

By M. Rice, M. Stanley, J. Marlow

Arizona construction aggregate industry remains in the crosshairs of public debate, caught between the need for aggregate-based building materials and alternative, high-value land-uses. To better manage lands and improve land-use decisions, the Arizona State Land Department has need for a system to assess potential aggregate resources on State Trust lands, and assign dollar values accordingly. Thereafter aggregate values can be compared to residential, commercial, agricultural, recreational, and habitat values -- in a determination of highest and best land-use.

Jan 1, 2002

By W. J. Miles

At the beginning of the 20th century, barite was a mineral of minor importance in the United States. Its primary use was to extend lead oxide in white paint. Barite also added the special qualities of hiding power and flatness to paint. Because white lead sometimes turns black or yellow and barite does not, ground barite became a pigment on its own merit. Barium chloride was added to bricks before fi ring to stop efflorescence when exposed to weather. Barium carbonate or nitrate added luster and brilliance to glass. Barium chemicals were added to refining sugar, enameling iron, making oilcloths and paper collars, and in the manufacture of paper, artificial ivory, rubber and lithopone. Lithopone became a major paint ingredient in the 1920s; its use lasted until the 1950s, peaking at 150 kt (165,000 st) of barite in 1937 and 1947 for the manufacture of lithopone. Later in the 20th century, titanium dioxide replaced lead oxide, barite and zinc oxide in the coatings industry. In the 21st century, barite is used as a filler, extender or weighting agent in products such as paints, plastics and rubber. Some specific uses include its use in brake and clutch pads for automobiles, automobile paint primer for metal protection and gloss, to add weight to rubber mud flaps on trucks and to add weight to the cement jacket around petroleum pipelines under water. In the metals casting industry, barite is part of mold release compounds. Because barite significantly blocks X-ray and gamma ray emissions, it is used as aggregate in high density concrete for radiation shielding around X-ray units in hospitals, nuclear power plants and university nuclear research facilities. Ultra-pure barite consumed as liquid is used as a contrast medium in medical X-ray examinations. Barite is the raw material for barium chemicals, such as barium carbonate, which is an ingredient in faceplate glass in the cathode-ray tubes of televisions and computer monitors. In the 21st century, barite industrial uses accounts for an estimated 78 kt/a (86,000 stpy) in the United States.

Jan 1, 2009

By R. Schwarz, E. Pusch, A. Juch

"The paper describes in general the objectives, goals as well as theoretical background of "METSI"-project proposal submitted to German BMBF (Federal Ministry of Education and Research). The METSI project is a starting point for technology and know-how transfer of German water management and water treatment technologies to South African Mining industry. "METSI" is Setswana, one of the eleven official languages in South Africa, and means "water". It stands also for "Management System for the Implementation of Environmentally Sound Water Supply Technologies in South African Mining Areas with Involvement of all Relevant Stakeholders". The project focuses on development, design and implementation of mathematical models that consolidate and evaluate existing data and generate substantiated projections of "water" amount and quality. METSI covers a wide range of scientific, technical, social as well as economic questions related to "water in mining"."

Jan 1, 2011

By M. L. Harris

In underground mines, coal dust explosions are prevented by the addition of rock dust sufficient to render the coal dust inert. The National Institute for Occupational Safety and Health (NIOSH) developed a hand-held instrument that uses optical reflectance to measure the explosibility of a rock dust and coal dust mixture. This instrument is called the Coal Dust Explosibility Meter (CDEM). In this study, NIOSH personnel accompanied Mine Safety and Health Administration (MSHA) inspectors on their routine band surveys in five underground coal mines in MSHA District 2 (Pennsylvania) and three underground coal mines in MSHA District 11 (Alabama). While underground, NIOSH personnel and MSHA inspectors used the CDEM to assess the explosibilities of the dust samples. The values of percent incombustible content (percent IC) determined by the CDEM agreed well with those obtained later by low-temperature ashing (LTA) in both MSHA and NIOSH laboratories. Further, the meter identified some samples as potentially explosible that LTA analysis had found to possess sufficient rock dust for inerting. The CDEM provides more information on the hazards in the mine. Rapid identification of areas with explosible dust mixtures using the CDEM allows for immediate intervention rather than a wait of several weeks for laboratory analysis.

Jan 1, 2008

By T. C. Souza Pinto

Because shape is an assessment of the three-dimensional form of a particle, it may be described in terms of sphericity (?), which is a measure of how closely a particle approaches a spherical configuration. In this study, Darcy?s law and the Kozeny-Carman model for fluid flow through porous media were applied to packed beds to determine the sphericity (?) of apatite particles. The beds were composed of glass spheres or particles of apatite (igneous from Brazil and sedimentary from the United States) of three classes of size (Class 1: -297 +210 µm; Class 2: -210 +149 µm; Class 3: -149 +105 µm). Glass spheres were used to validate the model because of its known sphericity (? = 1.00). Apatite particles, either igneous or sedimentary, showed very close values for particle sphericity (? ? 0.6). Observations on particle images conducted by scanning electron microscopy illustrated that igneous (? = 0.623) and sedimentary (? = 0.644) particles of apatite of Class 2 predominantly exhibit elongated shape. The close value of particle sphericity (? ? 0.6) showed by either igneous or sedimentary apatite may be justified by the similarity in particle shape.

Jan 1, 2009

By B. C. Vargas

The Toulon tunnel project is a key component of the Highway corridor on the French Riviera between Marseille and Nice and is a fundamental transportation infrastructure for the region. The first design studies started in the 1960?s. The tunnel project is made of 2 separate tunnels: South and North tunnel. The North tunnel was built between 1992 and 2002 after 10 years of difficult construction (for example, on March 15th, 1996, a collapse of the tunnel in the ?Marchand Area? generated a sink hole in the city Center, causing 20 months delay). The South tunnel alignment runs parallel to the North tunnel at the same depth below Toulon historical downtown (20 to 40m depth with some areas with less than 10m of cover). The Risk management program was studied to be a State of the Art program in urban tunneling construction. The Hydro Geological Context The whole project area is covered with backfills and colluviums of 1 to 4m thick. The Schist, marls and sandstones, randomly distributed along the alignment below the first layer have different characteristics. While the Schist are pretty compact, the marls are fractured. The other layers have very different characteristics, and many faults are located along the alignment, especially in the limestones. The Breccia are heavily decompressed and deformable, as well as the other soils located in the Marchand Area. This 80m long area is where the settlements need to be controlled with an extensive monitoring program. The complete Geological profile is presented in Figure 1. [ ]

Jan 1, 2012

By Wern-ping (Nick) Chen

The Florida Department of Transportation District 6 (FDOT D6) began a study in 1987 for a master plan to improve the traffic circulation and congestions between the Port of Miami (POM) and downtown Miami, FL. This study included a tunnel connection between two man-made islands, the Watson and the Dodge islands. Though a finding of no significant impact (FONSI) was completed in 1992, the project remained on hold for about 10 years. In 2002, Florida Turnpike took over this project, re-evaluated its benefits to the lo-cal communities, determined its feasibility (specifically the tunnel options) and established a probable cost. In 2005, the FDOT D6 regained its charge over the project and concluded that a bored tunnel under Biscayne Bay is feasible. Its primary components are: ? Widening of the MacArthur Causeway Bridge, to accommodate truck traffic to the Port of Miami. ? A tunnel connection between Watson Island and Dodge Island, where the POM is located. ? Connections to the POM roadway system, either for the traffic from the city of Miami or for the truck traffic from I-395 to the POM. The project will improve access to and from the POM and provide a dedicated roadway connector linking the POM with the MacArthur Causeway (State Route 41/1) and I-395, specifically for the trucks in and out of the POM without going through downtown Miami. As identified in the project information memorandum (PIM), its primary objectives are to: ? Improve access to the POM, helping to keep it competitive and ensuring its ability to handle projected growth in its cruise and cargo operations. [ ] ? Improve traffic safety in downtown Miami by removing POM traffic, trucks and buses from the congested downtown street network and, in doing so, facilitate ongoing and future development plans in and around downtown Miami.

Jan 1, 2009

By T. J. Nelson

Natural aggregates, primarily stone, sand and gravel, are recovered from widespread, naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size, and sold loose or in concrete products to build roads, houses, buildings and other structures. Smaller quantities are used in agriculture, cement manufacture, and chemical and metallurgical processes. The growth of cities, their buildings and the highways that connect them have created demand for enormous quantities of aggregates. Consumption has now reached 9 t (10 st) per person and continues to grow faster than population. The aggregates industry is the largest mining industry in the United States in terms of production by weight, by volume and by number of active operations. About 80 percent of the concrete pavement and more than 90 percent of the asphalt pavement is composed of aggregates.

Jan 1, 2006

By Ravi Ray, Kostas Kaklis, Zach Agioutantis

"Modern underground mining is becoming more complex and geotechnically challenging. The engineer uses numerical, analytical, and data-driven methods (empirical and/or experimental) or their combination to overcome these challenges. Each method has its advantages and disadvantages. Nevertheless, given the amount of innovation and experience involved in developing each of these techniques, it will be prudent to use all their benefits rather than favoring one technique over the other. Pillars are the most important support element in an underground mine. A holistic geo-mechanical solution needs to be determined to design mine pillars using a proper sequence and exact mix of the three methods. A combination of these methods, in sync, can encompass the several advantages of the three methods while eliminating their disadvantages. This paper presents a conceptual three-tier solution to the pillar design problem, to improve its design pedigree, using a proper combination of numerical, analytical, and data-driven methods. At the focus of this proposed method lies the Ground Reaction Curve (GRC) concept.INTRODUCTIONAlthough the stability analysis of underground excavations is a challenging problem, its understanding has improved tremendously over recent years through the use of improved tools and techniques. The trial and error method was replaced with more scientific methods like the empirical and analytical methods that are still in use today. Empirical methods were developed based on large data sets obtained from experiments and observations (e.g., coal pillar strength equations). Analytical methods were developed based on mechanical understanding of stability (e.g., safety factor for vertical pillar loading, Convergence Confinement Method). Improvement in computing power and numerical techniques led to the development of several numerical methods (e.g., finite difference, finite element) suitable for geo-mechanical analysis.Each of these methods have certain advantages and limitations. Nevertheless, the user is often puzzled over the proper method selection and over the proper sequence of using them. This exercise becomes more challenging when different methods are combined, where, for example, one has to estimate the pillar strength based on empirical equations (e.g., Mark-Bieniawski coal pillar strength equation), determine the factor of safety based on an analytical approach (e.g., tributary area load divided by pillar strength), and analyze pillar-strata interactions using numerical analysis (see Esterhuizen, Mark, and Murphy, 2010b).Challenges increase when current pillar design methods are designed as passive structures to balance the fixed dead weight of the overburden. This classic suspension design approach does not recognize the self-stabilizing capacity of the overburden (Frith and Reed, 2018). A practical solution to address these issues is the use of numerical analysis. However, one should always keep in mind that the numerical modelling approach may have certain practical limitations."

Jan 1, 2019

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.

By J. Donovan Jacobs

Many improvements in the art of underground excavation have appeared during the past two decades. These improvements have been both in methods and in machinery and have resulted in more economical construction of today's tunnels. In the realm of machines, the developments of continuous boring heads for either soft ground or rock, random arm excavators and the sliding tunnel floor (Magic Carpet) have each made contributions toward more rapid tunneling. CONTINUITY OF ADVANCE Tunnel boring machines are often referred to as "continuous excavators". Continuous advance (without cyclical interruptions) has not been achieved, however, in any of the machines now in use. In most rotary-head tunnelers the thrust needed to make the cutters bite into the face is obtained from hydraulic cylinders reacting against anchoring devices held stationary by pads which grip against the sides of the tunnel. With this system the forward motion of the cutting head is continuous only until the propelling cylinders have reached their limit of extension. At this point the grippers must be released, moved forward and reset before a new cycle of advance can be begun. Some machines are built to obtain their propelling thrust from hydraulic cylinders pushing backward against newly-installed rings of tunnel support. This is the customary method for propulsion of shields. With it, each cyclical advance or "shove" must await the erection of a new ring of supports. Faster tunnel driving

Jan 1, 1974

To gather additional field data from the western United States, researchers from the National Institute for Occupational Safety and Health (NIOSH) installed an array of field instrumentation at a longwall coal mine in Central Utah. The purpose of this field site was to monitor ground movement and changes in pressure during mining where conditions include massive, stiff overburden and relatively deep cover. To accomplish this, field instrumentation was installed in the two-entry gate road between the fifth and sixth longwall panel in the current mining district.

Jan 7, 2020

By W. Dan Hausel

More than 220,000 diamonds have been found in the United States that range from microdiamonds to 40.42 carats in weight (Table 1). Some reports suggest diamonds weighing more than 100 carats have also been found in this country, although these reports have not been verified. The source of most of the diamonds in the United States is a group of kimberlite pipes, dikes and blows in the Colorado-Wyoming State Line district and a group of lamproite pipes in the Murfreesburo, AR area. Other areas where diamonds have been found include the Great Lakes region, the Pacific Coast and the southern Appalachian Mountains. The latter two regions are generally not considered favorable for diamond deposits. This is based on exploration models. They suggest commercial diamond deposits will be restricted to kimberlites emplaced in Archean cratons and to lamproites emplaced in Proterozoic mobile belts accreted to the cratons.

Jan 1, 1995

By Jerry C. Tien

Mining in China dates back at least 4,000 years. Today, with no less than 103,000 metal/nonmetal mines and between 40,000 to 80,000 coal mines, China’s mining industry is undoubtedly the largest in the world. Despite improvements in recent decades, seemingly endless mining accidents continue to make the news. Official coal mining deaths were 6,702 in 2003, and 6,027 miners died in 2004; actual figures may be much higher. Added to these were the 2,699 deaths in the metal and nonmetal industries. Most of these accidents were due to CH4 (methane gas) explosions and fires as a result of inadequate mine ventilation de-sign or practices. A good portion of these accidents occur in small, privately run and often technically illegal mines. During the past 10 years, the Chinese government has attempted to crack down on small and often technically illegal mines without much success. The number of accidents and associated fatalities has not significantly reduced. However, there appears to be a new urgency in China’s efforts to step up mine safety in the country. After its worst reported mine disaster in more than a half century, the government quickly paid reparations to families, suspended high-level officials in charge and announced additonal reforms. One of those was the elevation of the central government’s work safety office to cabinet-level status. There has been increased transparency in reporting and investigation of mine accidents and disasters in recent years. There has also been an increase in public criticism by labor leaders concerning the neglect of mine workersafety.1 This article examines the causes of China’s many mining accidents, current legal and enforcement structures, respective mining health and safety related laws and regulations, recent mining industry developments and the latest effort to curtail small mining operations.

Jan 1, 2005

By Rick Frechette, Bryan Ulrich

Representatives from several mining operations in three western states left their mines behind for a day in February to discuss with their peers the issue of water. The event was Knight Piésold and Co.’s Roundtable 2007, held in Elko, NV. It was third such event put on by the company. The issue this year was site-wide water considerations.

Jan 1, 2007