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By Harry L. Siebert

A major Arizona highway project is jeopardizing site safety and security because of the lane rental policy. One million cubic yards of rock must be fragmented to provide two additional lanes parallel to the existing roadway. Traffic is stopped during blasting operations.

Jan 1, 1997

By G. Cherkashov

A new hydrothermal field with massive sulfide deposits was discovered in 2004 at 16º 38.4?N, 46º 28.5?W on the Mid-Atlantic Ridge. Hydrothermal signals had already been recorded from bottom waters and sediments in this area during cruise 19 of R/V Professor Logatchev in 2000. This site was revisited during the 24th cruise of R/V Professor Logatchev in February 2004 when samples of massive sulfides were recovered and video records of the deposits made. The basalt hosted hydrothermal field is situated at a depth of 3700-3750 m, 600 m above the inner floor on the eastern slope of the rift valley. Structurally, the new field is located at the intersection of a deep along-axis marginal fault and a transverse sub-latitudinal dislocation. Six sulfide mounds as well as associated metalliferous sediments were mapped (sampled and/or recorded by video profiling) within the hydrothermal site. The largest ore body, 500 x 225 m, in the southern part of the field consists of small blocky talus and relics of sulfide chimneys partly covered by iron oxyhydroxides. The chimneys are 1-5 m high. The southern and western boundaries of the massive sulfide deposit have not yet been delineated. More than 1,100 kg of massive sulfides and stockwork mineralization were sampled at 7 sites by dredge and TV-grab. Everywhere, iron sulfides were the principal minerals present. Pyrite in association with lesser amounts of chalcopyrite occurs in both massive sulfides and stockwork mineralization. Of particular interest is the chalcopyrite-siliceous stockwork where silicified and chalcopyritized basalts are intruded by a network of chalcopyrite veinlets. These zones could be fairly thick and enriched in base metals. Sphalerite was very rare.

Jan 1, 2004

By Brian Wilson, John Scholte, Megan Atkinson

"In November 2004, the residents of the City of Nanaimo, B.C., Canada voted to approve a new conference centre as the centrepiece of a proposed revitalization project for the city’s historic downtown core. The proposal goal was to replace a cluster of derelict buildings with a dynamic and modern complex that would connect existing city facilities to a new conference facility, the Vancouver Island Conference Centre (VICC). The conference centre is expected to create 150 full-time jobs, attract visitors/ delegates from across North America and generate new economic opportunities for local businesses.However, the proposed site posed a number of geotechnical and geoenvironmental challenges. As is often the case with coastal cities, historic growth of the Nanaimo downtown and harbour area was achieved through reclamation of former waterfront areas and inlets. These areas were often infilled with random fills and even wastes, leaving a legacy of variable density heterogeneous fills contaminated with a variety of pollutants. Preliminary assessment of the site indicated a high likelihood of a requirement for deep foundations, a high risk of liquefaction in the event of an earthquake and the presence of both soil and groundwater contamination. Construction would be further complicated by the requirement for two levels of basement parking and the proximity of adjacent buildings and major roadways to the work area.With a limited budget (fixed by the referendum) and timeframe, the city needed a cost-effective solution to proceed with construction. A number of options were considered, but an innovative design using leading-edge Cutter Soil Mixer (CSM) technology best met the geotechnical and budgetary requirements of the site. The CSM approach also addressed the environmental concerns of contaminated soils and groundwater. Golder Associates Innovative Applications (GAIA) Inc., in association with the designers of their parent company Golder Associates Ltd. (Golder), proposed the CSM technology — at the time the first North American application."

Jan 1, 2008

By William Reisz

Managing the blast site at almost any operation can be a daunting task. There are so many details that must be observed, understood, and acted upon. It goes without saying that there are no two locations that have the exact same challenges and concerns. The level and the extent of these challenges can vary widely.

Jan 1, 2014

By R. D. Williams

"In a very real sense, Butte, MT is where the copper came from that won two world wars. The price for that unrestricted mining and smelting of copper came due in 1983 when Butte was declared a Superfund site.One of the most complex remnants of this mining history is the Parrot Tailings site. The Parrot smelter operated from 1881 to 1910, moving Upper Silver Bow Creek to the south and depositing approximately 283,000 m3 (370,000 cu yd) of waste material adjacent to Upper Silver Bow Creek. Additional mixed waste from other processing sites deposited below the Parrot tailings at the Northside Tailings, Diggings East and Blacktail Creek Berm total approximately 171,000 m3 (224,000 cu yd) of contaminated material. As part of the Superfund remedy, the U.S. Environmental Protection Agency (EPA) proposed leaving all these wastes in place. This proposal prompted a detailed criticism by several geoscientists familiar with the site. The EPA’s 2006 Record of Decision (ROD) did in fact leave these wastes in place, which set the stage for a series of studies that continue to refine how best to protect extensive completed Superfund Remediation downstream of Upper Silver Bow Creek. History of the Parrott Mine and tailingsPlacer gold was discovered in Silver Bow Creek, the headwaters of the Clark Fork River only a few miles from the Continental Divide in 1864. This discovery led to a stampede of placer and lode claims. One of the first lode claims located was the Parrot lode, located in the fall of 1864. Progress for developing a mine at the Parrott was slow, and it was not until 1876 that one of the original locators encountered a rich vein of chalcocite. Butte had its first copper mine.The Parrott Mine was patented in 1879 and by 1881 the Parrot, having lost a “t”, concentrator and smelter were built. The smelter and concentrator were an immediate success with a considerable market for processing the district’s rich copper ore. In 1885, the employees of the Parrot smelter bought the Butte Reduction Works, another smelter. In 1885, dams were built on Silver Bow Creek to contain various tailings and related processing byproducts (Fig. 1).By 1890, the various smelters in Butte rendered Butte’s air quality as suffocating (Fig. 2). An 1889 funeral procession was rumored to have gotten lost in the thick smelter smoke and somehow ended up at the Centennial Brewery. A city ordinance was passed late in 1890 in an attempt to control smoke. The Parrot smelter employed approximately 500 men by 1890. Through the 1890s, the tailings produced grew from approximately 91 t/d (100 stpd) to more than 181 t/d (200 stpd). Copper values in the tailings were initially as high as 4 percent, but as the processing improved that was reduced to 1.5 percent."

Apr 1, 2019

By David G. Paton

"Electromagnetic surveys were conducted at the BXL Bulk Explosives Limited Mixing Plant andsurrounding area to characterize runoff from the site and possible impacts of salinity. The BXL Plant is located at the edge of a depressional area and any escape of soluble ions, such as nitrates, would have ended up in the slough to the west of the plant. Two electromagnetic (EM) instruments were used in the survey. A Geonics EM 3 1 was used in October 1997 and in June 1998, a new multifrequency instrument, a GSSI GEM 300 was also tested. Both instruments were individually mounted on a plastic sled with Teflon runners and towed with an ATV quad. Position was determined using a Trimble Pro XL global positioning system (GPS) with a real time correction mode Landstar receiver for an accuracy of about *l m. Both GPS and EM instruments were set to collect data at 1 second intervals. The quadrature maps for both instruments showed essentially the same information, namely of very high conductivity, appearing to emanate from the mixing plant. The levels of conductivity were highest where the saline water appeared to pool, at the southern end of the slough. Soil sampling locations were identified from the EM maps and navigated to using the real time GPS. Composite samples were collected by hand using a Dutch auger, from two locations, in increments of O-1 5, 15-30, 30-60 and 60- 90 cm. The analysis of the soil samples indicated a complete absence of nitrate or ammonium ions; the major anion was sulphate, indicating naturally saline subsoil conditions. The GEM 300 made the collection of data more efficient, as only one pass was required to collect the data from four depth intervals. The EM survey combined with the real time GPS allowed rapid characterization of the site with respect to soil salinity and proved to be cost-effective for Phase l/ Phase 2 site assessments and targeting sampling locations."

Jan 1, 1999

By Georgette Hlepas

How often phrases like these have been made by project managers and project teams trying to explain why there has been cost growth, project delays and differing site conditions claims. But does it really take x-ray vision? Do we really approach geotechnical construction projects unprepared for the subsurface that may be encountered because we can't get the answer? Too often our industry seems to think the answer is, "yes." However, this is not because we can't understand the subsurface. All too frequently it is because a choice is made to save money or time by foregoing or shortchanging upfront subsurface investigations. This is accepting a risk at the beginning of the process and realizing it during construction. Case histories have proven time and time again that upfront investment in site exploration and constructing a ground model mitigates risk in design and construction. But how much do we prepare? What level of investigation (or investment) is appropriate? The answer of course, is it depends; how much risk are you willing to take for your project and what are the potential consequences?

May 1, 2022

By David E. Siskind

"This report describes recommended vibration monitoring and assessment practices at blasting sites.Intended is regular monitoring, tracking of trends, responding to complaints of alleged damage, and the technical and data aspects of addressing lawsuits."

Jan 1, 1999

By Lee S. Vanzler

Atlantic Wharf involved the construction of a six-level underground parking garage and a 32-story high rise tower along the historic Boston Harbor waterfront. The site, historically known as ?Russia Wharf,? consisted of filled land initially created in the late 1800s by extending the shoreline toward the harbor as the urban population and land needs grew to support expansion of commerce and trade. Redevelopment required solutions to address relics of waterfront structures (granite block seawalls, piles, and piers), weak subsurface soil conditions, tidal groundwater levels, and contaminated soils resulting from previous site usage and filling. The foundation system, consisting of drilled shafts with column loads up to 14,000 kips (62,272 kN), concrete diaphragm wall (slurry wall), and up-down construction methodology, was chosen to address these factors. As a prerequisite for development, selected portions of the façades of the former historic buildings were required to be preserved, protected, and incorporated into the final building configuration. The historic façades were temporarily braced and supported prior to the demolition of the buildings and commencement of below-grade construction. This paper will describe the considerations in the selection of up-down construction methodology along with a discussion of the design and performance of the concrete diaphragm wall and drilled shaft foundations. Up-down construction methodology shortened the overall construction schedule while addressing the lateral bracing requirements for the concrete diaphragm wall and restrictive ground movement tolerances to protect adjacent structures. Below-grade construction was completed in March 2010, and the building was opened for tenant occupancy in January 2011.

Jan 1, 2011

By P Rubie, J Russell

This paper looks at the past, present and not too distant future of grinding mill relining.Since the adoption of autogenous grinding (AG) mills and semi-autogenous grinding (SAG) mills as the primary ore reducing devices in the comminution circuit, plant shutdown frequency and duration has largely been driven by the liner maintenance requirements of these mills.The past 30 years have seen the introduction of many technologies to reduce relining times and frequencies. Advanced relining systems have been developed which include single and twin Mill Relining Machines, capable of placing large (up to 8000 kg) liners, high energy recoilless THUNDERBOLT Hammers, and high capacity Feed Chute Transporters. Despite these advances, today many of the hazards associated with mill relining remain and reline times still vary considerably between mine sites. A sophisticated discrete event simulation program, designed to analyse the mill relining process, has revealed the dominant influences on reline times of crew performance and of the need for safe access to larger segments of the mill.A new generation of advanced and semi-automated technologies is currently being tested that will address these remaining challenges. These technologies remove people from the hazardous environment inside the mill and will allow techniques used in modern advanced manufacturing to provide a near-future step change in mill relining safety and performance.CITATION:Rubie, P and Russell, J, 2018. 21st century relining – the path to greater mine site profitability, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 621–640 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By L. A. Pursell

Environmental constraints can both delay and raise the cost of a major plant addition, often requiring a complete reevaluation of the plant site and the proposed project. In this case history, steps are presented which were followed in applying for environmental permits for a major addition to a lime plant. Methods are described for determining expected emission increases and for selecting the best control technology for each source. The description progresses through pre-application conferences with control agencies, the formal application procedure, computer modeling the air quality impact, and the methods followed in obtaining a favorable determination.

Jan 1, 1983

By S Fidler

Underground coal gasification (UCG) is a process by which coal is converted in situ to a combustible gas that can be used as a fuel or chemical feedstock. The process has been used in commercial-size projects in the former Soviet Union for more than 40 years, while significant national research programs have been undertaken in the United States and Western Europe. The Chinchilla UCG project is located at a site southeast of Chinchilla in Queensland. The UCG operation commenced in December 1999. A controlled shutdown of the process was initiated in January 2002 and successfully completed in April 2003. The process is currently under conservation and ready for restoration of gas production for commercial use in the near future. Groundwater plays an important role in the gas formation process during UCG. Most of the process water required for chemical reactions is usually derived from the coal seam itself and from surrounding aquifers. If insufficient water is available for chemical reactions the UCG gas will contain reduced concentrations of combustible components, and conversely, excessive water influx into the process area would cool down the reactor and thus limit the energy available for gas production reactions. Because of the importance of groundwater in the gasification reactions, and the potential to contaminate groundwater if the process is not correctly controlled, it is essential to predict and to control the groundwater influx into underground gasifiers during and after underground gasification. Control of groundwater requires a thorough understanding of hydrogeological conditions in the vicinity of the gasifier in order to be able to predict inflow rates, and constant monitoring throughout the process of water production rates and groundwater pressure in the coal seam and adjacent aquifers. Hydrogeological testing and groundwater monitoring in the vicinity of the UCG operation commenced six months in advance of its initiation. Monitoring of groundwater pressures in the vicinity of the gasifier have also been undertaken using vibrating wire piezometers installed in the coal seam at varying distances from the gasifier. This paper presents the results of the hydrogeological testing and groundwater quality monitoring carried out at the site, which show that it is possible to operate a UCG process without uncontrolled impacts on groundwater.

Jan 1, 2003

By L. W. Saperstein, M. C. Radomsky, D. L. Passmore, J. D. Bennett

About 60 small surface coal mines in Pennsylvania participated in a program designed to improve safety performance in the workplace. The method involved the use of safety sampling and observation to assess the degree of safety exhibited by workplace behavior and conditions. Data were collected through the use of on-site safety instruments covering seven major occupational positions typical of small surface mines. Workplace events observed (acts and conditions) were assigned a hazard classification. Feedback was initiated to improve safety performance in areas failing to conform to appropriate safety standards. Results suggest that the variety of unsafe acts and conditions associated with the companies observed are extensive. Further, the experiences drawn from this pilot project have proven the need to pursue this behavioral approach. Future research should concentrate on subjecting the present approach to a strict experimental design involving randomly selected “poor risk” mines.

Jan 1, 1987

By Harry Verakis, Thomas Lobb

Widespread use of ammonium nitrate compositions for mine blasting operations has led to various bulk transport vehicles designed especially for the explosives industry over the past half century or more. The advancements in explosives technology and continuing developments in bulk transportation have resulted in a variety of blasting agents and, more recently, oxidizers being transported and used from specially designed bulk transport vehicles. It is estimated that about 2000 bulk transport vehicles are used in mining operations. Many of the bulk vehicles carry about 15,000 to 33,000 pounds (6808 to 14,968 kilograms) of payload and some can carry up to 50,000 pounds (22,679 kilograms) for large open cast mines. Thus, it is imperative that detailed knowledge and safety instructions are available from the blasting personnel and mine management should an unplanned incident such as a fire occur with a bulk transport vehicle at a mine site.

Jan 1, 2008

By Ralph Musick, Brian Briggs

The U1h Shaft Project is a design/build subcontract to construct one 6.1 meter(m) (20 feet [ft.]) finished diameter shaft to a depth of 321.6 meters (m) (1055 ft.) at the Nevada Test Site (NTS). Atkinson Construction was subcontracted by Bechtel Nevada(BN) to construct the U1h Shaft for the Department of Energy (DOE). The project consists of furnishing and installing the sinking plant, construction of the 321.6 m(1055 ft.) of concrete lined shaft, development of a shaft station at a depth of 297.5 m(976 ft.), and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper will describe the design phase, the excavation and lining operation, shaft station construction and the contractual challenges encountered on this project.

Jan 1, 2001

By Dharmil Patel, Michael J. Chow

"Construction progress is nearing completion at a Brownfield Site for a 100,000sf mixed-use 10 story building plus cellar for Silver Star Motors including a two-floor pre-owned Mercedes Benz showroom; high-end residential rental studios, 1, 2, and 3 bedroom apartments; and penthouses on the upper two floors. Excavation through impacted soil extended to 15ft depth. Project is approximately 7 ft north of a NYCT subway station, portions of the SOE are within inches of a 6ft diameter NYCDEP Sewer, and cellar extends below the depth of adjacent structures, requiring over 200 lf of underpinning.A complex series of earth retention systems was utilized consisting of underpinning, drilled-in soldier piles (micro-piles), timber/concrete lagging, soil anchors and inclined rakers supported by a partially constructed foundation mat. Foundation mat subgrade was approximately 4 ft below the groundwater level creating more challenges during underpinning and achieving suitable foundation subgrades. All construction was undertaken on a non-union basis.This paper describes the design, construction, and lessons learned for the multiple earth retention systems, Brownfield Remediation requirements, instrumentation, and monitoring used to manage complications of building adjacent to an active subway station, in close proximity to existing utilities, with underpinning and mat foundation installation below the water table.Results of the instrumentation program are summarized which utilized an AMTS, monitoring prisms on adjacent structures, automated seismographs, and manual NYCT surveys."

Jan 1, 2016

By Mark G. Lafontaine

Underground 802.11 wireless communications has become widely adopted for automation and communication purposes but maximizing the wireless signal presents many obstacles given the harsh environment as well as the presence of materials and conditions that can reduce signal propagation. Changes in elevations and curvatures in ramp to drift transitions also affect the wireless signal. Based on the requirements of wireless applications such as voice, data, or location tracking, the wireless site survey is the key tool for measuring and predicting signal strength and signal-to-noise ratio. These readings help determine the maximum distance between access points in order to sustain an overlapping wireless signal where required. This paper describes the methodology and tools used for measuring 802.11 wireless signal strength in an underground mine environment in Northern Ontario. The physical characteristics of the mine and the actual recorded wireless signal data will be presented in order for the audience to gain an understanding of the factors that affect signal throughput. Antenna selection used for the site survey will also be discussed as it played a key role in propagating the wireless signal.

May 1, 2013

By Mills KW

Coal mine pillar design formulae available to mine planners are typically based on relationships determined for specific site conditions. Application of these methods is difficult when other factors, relating to mining or geological conditions, not specifically addressed in these relationships are encountered. A review of pillar design methods, coal strength properties and relevant field monitoring of pillar behaviour has shown pillar strength and deformational characteristics are extremely sensitive to in situ behaviour of the rock and other material components that make up the coal pillar system. A method has been developed that has been found to provide excellent correlation between existing field data using the strength and deformational characteristics of materials determined in selected laboratory tests. This method is based on definition of the loading conditions, accurate modelling of the strength, confining conditions and deformation occuring in the roof, floor and coal seam and definition of the in situ strength of coal based on underground monitoring of appropriately sized coal pillar. The design method is considered to provide an accurate and rigorous pillar design method that will give mine planners a more rational mine design capability which is based on the mine geometry and geological setting of the operation. It is envisaged that availability of such a method will allow significant optimisation of pillar layouts and more closely define the geological and mining issues that relate to pillar design optimisation.

Jan 1, 1992

By Winton J. Gale

Coal mine pillar design formulae available to mine planners are typically based on relationships determined for specific site conditions. Application of these methods is difficult when other factors, relating to mining or geological conditions, not specifically addressed in these relationships are encountered. A review of pillar design methods, coal strength properties and relevant field monitoring of pillar behaviour has shown pillar strength and deformational characteristics are extremely sensitive to in situ behaviour of the rock and other material components that make up the coal pillar system. A method has been developed that has been found to provide excellent correlation between existing field data using the strength and deformational characteristics of materials determined in selected laboratory tests. This method is based on definition of the leading conditions, accurate modelling of the strength, confining conditions and deformation occuring in the roof, floor and coal seam and definition of the in situ strength of coal based on underground monitoring of appropriately sized coal pillar. The design method is considered to provide an accurate and rigorous pillar design method that will give mine planners a more rational mine design capability which is based on the mine geometry and geological setting of the operation. It is envisaged that availability of such a method will allow significant optimisation of pillar layouts and more closely define the geological and mining issues that relate to pillar design optimisation.

Jan 1, 1992

By Konner Horton, Adam L. Bedell, Don Del Nero, Brian Jones

"The City of Atlanta’s Water Supply Program Tunnel project includes a 7,315-m (24,000-ft) long, 4-m (13-ft) diameter, hard rock tunnel. A complex aspect of the project involves connecting five, blind bore shafts to the tunnel in a location close to current drinking water reservoirs. During the supplemental geotechnical investigation following the initial contract award, results from additional borehole geophysics were reviewed. Unfavorably oriented fracture sets forced a change in the original pre-excavation grouting program designed for that site. Real-time grout monitoring and geophysical data were compared to provide assurance that the program, as designed, correlated with the in situ ground conditions. Following grouting, results were modeled, and all grouting data were reviewed to determine if grouting was complete.Project backgroundThe current water supply system operated by the city of Atlanta’s Department of Watershed Management (DWM) consists of four, aged, raw-water pipelines, one of which dates back to 1893. Based on previous assessments completed by the DWM, the entire water supply system is at, or will soon reach, its recommended useful life. As such, the city acquired the Bellwood Quarry in 2006 with the intention to create a water storage facility with a volume of approximately 9.1 billion L (2.4 billion gal) to serve approximately 1.2 million people.The project location is shown in Fig. 1, which is generally in the northwest part of downtown Atlanta, GA. The overall project has been divided into two phases. The Phase 1 project connects the quarry and the Hemphill Water Treatment Plant (HWTP), and the Phase 1 Extension project connects the HWTP to the Chattahoochee Water Treatment Plant (CWTP) and the Chattahoochee River. A 7,315- m (24,000-ft) tunnel with a finished diameter of 3 m (10 ft) connects all three elements. The HWTP location is also where the city’s two most proximate drinking water reservoirs are located."

Jan 9, 2018