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The Douglas mineral sands deposit is located 75 km north of Hamilton in western Victoria, Australia. The deposit was discovered in the late 1990s by Basin Minerals Limited and purchased by Iluka Resources Ltd in 2002. Prestrip mining commenced in December 2004, with ore mining commencing in August 2005. Douglas is the first of several projects being implemented by Iluka Resources Ltd in the Murray Basin, with all heavy mineral concentrate planned to be treated at the companyÆs mineral separation plant in Hamilton. The mineralisation at Douglas lies along the south-eastern margin of the Murray Basin. It is hosted by marine Pliocene Loxton-Parilla Sands and consists of three discrete deposits; Bondi Main, Bondi West and Bondi East. The mineralised sediments dip at a low angle to the west and lie unconformably beneath a veneer of top soil (50 - 100 mm) and subsoil (up to 600 mm) and between three to 12 m of overburden. The barren overburden, characterised by high clay content (<53 ¦m material) generally provides a stark contrast to the sandy ore, which is between 1 m (parts of Bondi East) and 15 m (Bondi Main) thick. Both overburden and ore are removed utilising standard dry mining techniques using both scraper-bulldozer and truck-excavator combinations. All ore is delivered to run-of-mine (ROM) stockpiles before being reclaimed by front end loader into the processing plant. Grade control at Douglas is based around visual dig control aided by high precision survey, which enables accurate reference to the resource drilling and block model data. Vertical excavator faces, inclined scraper faces plus regular test pits and trenches provide opportunities for in pit mapping and sampling. This data is used to refine not only the resource estimate for Douglas but also the drilling, interpretation and resource modelling methods used for similar deposits across the basin. The foundations of the geological reconciliation process at Douglas are the in pit surveys undertaken each time the mining fleet has completed building a ROM stockpile. These surveys and the subsequent interrogation of resource models enable robust estimations of the heavy mineral content of the stockpiles, which are subsequently used to predict the daily input grades into the plant during their reclamation. Reconciliation of this daily data is then undertaken at the end of each month against metallurgical production data and plant balances. Learnings and results from the reconciliation process are used to further refine subsequent resource models and modelling methods.

Jan 1, 2009

A list of permissible mine equipment approved by the Bureau of Mines before January 1, 1937, was published in Bureau of Mines Information Circular 6942.3/ Information Circular 7007,4/ published as a supplement thereto, listed equipment approved. Burin', the calendar year 1937. The present list includes most of the material liven in these two publications, as well as approvals that have been issued up to January l, 1940. Some equipment formerly listed has been omitted because it has become obsolete or is no longer actively marketed. The list now includes electrically-operated air compressors, coal drills, loading machines and conveyors, mining machine, mine ones, rock-dusting machines, room hoists, storage-battery gathering and haulage locomotives and storage-battery power trucks, mine telephones, junction boxes, electric cap lamps, flame safety lamps, electric hand and trip lamps, electric flood lens, flashlights, methane detectors, and single and multiple-shot blasting units. The appendix at the end of this circular lists trailing, cables that have passed tests prescribed by Schedule 2D. When equipment passes the inspections and tests prescribed by the United Status Department of the interior, Bureau of Mines, in published "schedules" or standards, it is formally approved as "permissible" for use in gassy mines, and the manufacturer is then permitted to mark it with an approval plate that identifies it as having been approved by the Bureau. The inspections and tests are designed to insure that each equipment satisfies the minimum requirements for safety in use. The Bureau's purpose in investigating equipment of this type and listing that

Jan 1, 1940

By William L. Crentz

This study of the preparation characteristics of the coals in Indiana County, Pa., is the second in a series of Bureau publications appraising the Nation's coking-coal reserves by counties and the practicability of upgrading marginal deposits to metallurgical standards. The first publication dealt with the preparation characteristics of the principal coal beds in Cambria County, Pa. Over 95 percent of the coal remaining in Indiana County is in the Upper Freeport, Lower Freeport, and Lower Kittanning beds. Isolated patches of Pittsburgh-bed coal are present, and the Upper Kittanning bed is found in minable thickness at some locations, but production from these sources is not large. The greatest production is from the Freeport beds, which account for nearly 70 percent of the Indiana County coal output. These beds usually contain two or more shale or hone partings and in many places are high in sulfur. The large proportion of bony coal in the Freeport beds 'produces a relatively high-ash product. Mining practices vary from place to place, but it is frequently necessary to leave certain bony portions of the bed in place in order to load a satisfactory product. Table 1 shows the county's coal production, by beds, during 1948.

Jan 1, 1951

By Luiz Henrique Accorsi Gans

First, this works carries an experimental evaluation for austempered ductile iron (ADI) as a gear material. And second, in order to provide a better understanding of the microstructural effect on the stress state of subsurface regions, a finite element method approach was considered using the submodeling tool in ANSYS 11.0. For this, ADI gears were produced from continuous cast iron bars, heat and thermochemical treated and tested in FZG test rig. The results were compared to those of carburized steel AISI 8620 and induction hardened steel AISI 4140 gears. The wear experiments were performed at the temperature of 90ºC with two torque stages: 135 N.m (running-in) and 302 N.m (steady-state). The time for pitting and spalling on the gears surfaces were measured using image analysis. The results showed a very good potential of using ADI for manufacturing gears, replacing induction hardened steels. Also, the ADI gear with smaller nodules showed higher life for pitting. In contact fatigue tests with severe load, the carburized AISI 8620 steel proved more adequate than the austempered ductile iron, showing that the mechanical properties are critical in the resistance to damage in gear contact. The austempered ductile iron with smaller nodule size showed to be very competitive with wear resistance similar to AISI 4140 steel induction hardened. With ANSYS, it was verified that the nodule size affects the gears life independently of the mechanical properties of the matrix. The results showed that the nodules indicate the presence of a concentration stress, but their size doesn’t affect the contact fatigue life as much as the total amount of nodules, regardless of the ductile iron microstructure. The size and number of nodules affects both the nucleation and the propagation stage of cracks. ADIs with higher amount of nodules have a greater wear resistance. Also, compared to the Hertz contact theory (isotropic material), the presence of graphite nodules indicates a non-isotropic material and made the maximum shear stress point moves toward the surface.

Jul 31, 2018

By Jürgen F. Brune, SAMUEL A. LOLON, ADITYA JUGANDA, Gregory E. Bogin Jr

Historically, there have been many occurrences ofmine fires and explosions recorded in the United States and other countries that have demonstrated the existence of explosivemethane–airmixtures, herein referred to as explosive gas zones (EGZs). The risk of mine explosions can increase if the EGZs migrate out from the gob into the surrounding mine entries. Fluctuating barometric pressure is the common cause for EGZs outflowing or outgassing from the gob. Numerical analysis using a 3D computational fluid dynamics method was developed to fully understand the outgassing phenomenon. A number of simulations using various magnitudes and periods of barometric pressure changes indicated that the EGZ outgassing potentially occurs due to lags in pressure, which are strongly influenced by mine conditions and ventilation systems. An early warning system with a real-time pressure monitoring and the application of gob ventilation boreholes are recommended to detect and mitigate explosion hazards from gob outgassing.

Aug 24, 2020

By James F. Devine

This Bureau of Mines report describes tests conducted at three sites to determine if, and to what extent, a vertical presplit fracture plane placed between a blast point and detection point will reduce vibration levels. Statistical analyses indicate that the presplit fracture plane did not reduce the vibration level.

Jan 1, 1965

By W. R. Clark, W. W. Cotter

Jan 1, 1946

By W. W. Cotter, W. R. Clark

Jan 1, 1946

By J Krnmmelbein, T Raab

In Lusatia, lignite mining causes major disturbances on the landscape scale. Reclamation procedures are applied to recover the reconstructed landscape for different land use options. In this study we investigate soil physical properties of an agricultural reclamation/recultivation site directly after site restoration and the development of selected parameters within the first years after site restoration depending on varying recultivation strategies.The sandy substrates used for recultivation stem from depths of several meters. They are unstructured, free of recent organic matter and have high contents of calcium carbonate. During reconstruction and most of all during surface levelling with heavy crawlers, the substrate?undergoes high mechanical stresses. This leads to partly severe soil or substrate compaction, depending amongst others on substrate water content and mechanical stresses during site construction. We investigate the effect of different organic soil amendments, different crop rotations and partly subsoiling on the development of soil structure. We compare results of laboratory measurements directly after site construction before any reclamation measures had been applied to results we gained after three and four years of recultivation. The results show that after the earthworks are completed, the site is strongly heterogeneous in relation to mechanical stability, permeability for air and water, pore volume and bulk density. The results after three and four years show that the heterogeneity of soil physical parameters decreases. The selection of suitable crop rotations superimposes the affects of other reclamation measures, eg varying organic fertilisers or deep loosening.CITATION:Krnmmelbein, J and Raab, T, 2012. Reclaimed lignite mining areas A73 in Lusatia - Development of soil physical parameters of an agricultural site within the first years after site reconstruction, in Proceedings Life-of-Mine 2012 , pp 117-122 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By T. Kessler

The purpose of this investigation was to evaluate the application of a spark-source mass spectrograph equipped with a spinning-electrode system for the study of various high-molecular-weight materials derived from coal. Conclusions from the investigation of anthracene, phenanthrene, chrysene, coronene, truxene, a coal-tar pitch (800 to 850 C softening point), and anthracene-chrysene synthetic mixtures follow: 1. Simplified mass spectra of anthracene, phenanthrene, chrysene, coronene, and truxene, from which the molecular weights were easily determined, were obtained by the spinning-electrode system. 2. Eight structural types having molecular weights from 178 to 252 corresponding to compounds previously observed in an electron impact mass spectrum of a coal-tar pitch sample were affirmed by this technique. 3. Mass spectra obtained from synthetic mixtures of anthracene and chrysene demonstrated that the technique is applicable for semiquantitative analysis.

Jan 1, 1967

By Néstor D. Córdova

El presente trabajo revisa las técnicas empleadas y las condiciones previas para el sostenimiento y construcción del tunel Gandolini de la unidad minera Julcani. En esta perspectiva, el túnel sirvió de base para realizar las investigaciones de campo, obteniéndose así la información básica para un mejor entendimiento del comportamiento del macizo rocoso con miras a la solución de los problemas que planteaba su construcción. Por ello, la mecánica de rocas como técnica empleada, evalúa la alteración al equilibrio del macizo rocoso en el que se construye el túnel. Asimismo, se establecen criterios para la determinación de las cargas del techo y se los relaciona a los diferentes parámetros de diseño para llegar al cálculo del sostenimiento, dándose finalmente los aspectos prácticos relacionados a la selección de los tipos de sostenimiento más adecuados.

Oct 14, 1980

By N. N. Breyer

A specially built "hard" tensile machine with characteristics permitting the precise detertnination of the drop of the load at the yield point has been used to study the magnitude of the yield-point phenotnenon in prestrained martensitic 4340 steel. A new phenonzenon, the appearance of a secondary yield point, has been observed by holding the specimen at constant strain in the plastic region. Furthermore, it has been found that a series of yield-point drops could be introduced by successive constant strain holds in the plastic region. The isothermal kinetics of the development of the secondary yielding point lave been studied at four temperatures: 24° 0° -18°, and -79°C. From the results of the kinetic investigation, equations for the In a previous investigation1 it was shown that, contrary to generally held opinion, steels of medium carbon content, such as 4340, 4140, and 86B30, in the as-quenched martensitic condition, can be cold-drawn through a die with reductions in area of up to 10 pct without cracking. Tensile specimens of 4340 machined from bars quenched and prestrained in this manner exhibited tensile strengths of about 400,000 psi coupled with 30 pct reductions in area. In addition, it was found that each sample of such steels exhibited a yield point in the quenched, cold-drawn condition. Since these studies were conducted on a commercial hydraulic testing machine of a type which is not well-suited to detailed study of yield-point behavior, it was decided to study this phenomenon more thoroughly on a rigid straining machine. In this new investigation, use of such a "hard" machine not only allowed study of the magnitude of the yield-point drop but also revealed a new phenomenon—secondary yielding of the martensite introduced by stopping crosshead motion after plastic deformation of the sample had begun. The present paper is a report of these findings. MATERIALS AND PROCESSING The material used was a commercial 4340 steel of the composition shown below: 0.41 0.80 0.013 0.019 0.31 0.85 1.76 0.28 1 0.42 0.77 0.015 0.024 0.30 0.84 1.69 0.28 0.08 2 1 = Ladle analysis. 2 = Laboratory analysis. Bars of this steel were processed in the following way: 1) machined to predetermined diameters; 2) austenitized at 870°C for 1 1/2 hr; 3) oil-quenched; 4) cooled to -115°C for 1/2 hr; onset and increase in magnitude of the secondary yielding in this temperature region have been found to fit the relationship ?Ys = Atn where ?Ys is the magnitude of the secondary yield Point in psi, t is the time in seconds, and A and n are parameter characteris-tics of the material. Although the occurrence of the primary and secondary yield points could be rationalized qualitatively on the basis of stress-induced ordering of carbon atoms in the stress fields of dislocations, as postulated in an earlier paper, the kinetics of the secondary-yield-point development were interpreted to indicate that the ordering involves more than just single jumps of carbon atoms from high-energy to neighboring low-energy sites. 5) pickled and lime-coated; 6) drawn through a carbide die. The predetermined diameters were chosen so that drawing through the same die gave the various reductions desired. Tensile specimens of 0.252 in. diam with a 1 1/4 in. gage length were then prepared from the drawn bars and tested. In order to study the stress-strain behavior at the yield point in detail, a rigid tensile machine with a high spring constant was constructed. Columns of large cross section (relative to the specimen cross section) constituted the machine frame. A dc motor was used to drive a screw via a gear reducing train and a "crane" thrust bearing. In this relatively simple device small deformations could be observed un-blurred by the slow response and lower spring constant inherent in hydraulic machines.' A strain-gage dynamometer permitted load changes as small as 8 lb to be read. RESULTS Tensile test samples machined from bars in the as-quenched condition with no subsequent drawing and samples from bars with 3.8 pct reduction after quenching gave stress-strain curves typified by those shown in Figs. I and 2. The time lapse between predrawing and tensile testing varied but usually ranged between 3 to 6 days at room temperature. The strain rate during testing was 0.003 in. per in. per min. The as-quenched curve is seen to have a broad serrated maximum whereas the stress on the specimen prestrained 3.8 pct rose linearly to point A, Fig. 2, fell abruptly to B, and then gradually to C. The abrupt drop to B was accompanied by evidence of incipient necking. The drop of the stress at the yield point in the prestrained samples (A to B in Fig. 2) changed with the percent prestrain, as illustrated on Fig. 3. Although the tensile strength increased continuously with the amount of previous cold drawing, the magnitude of the yield point drop first increased—up to about 6 pct prior reduction—and then decreased. Specimens from bars predrawn more than 8 pct broke in a brittle fashion in the elastic portion of the stress-strain curve.

Jan 1, 1967

By B Y. Luan, Y Tian, W Zhou, X Lu, Q X. Cai

The unmanned driving technology in open pit coalmines is an important technology that relies on innovation to drive the development of the open pit coal mining industry in China’s transformation of growth drivers and industrial structure upgrading. It is an important path to solve the shortage of mine truck drivers in the future mining, an important way to improve the working environment of open pit mining personnel, and an important foundation for achieving flexible production capacity in open pit mining to cooperate with the coordinated development of new energy. The communication rules at intersections are key to ensuring the safety and efficiency of unmanned driving in open pit coalmines. This paper proposes a collaborative traffic strategy between unmanned trucks for the single bucket unmanned truck intermittent process system in open pit coalmines. Based on the gap theory, this paper analyses the conflict characteristics and establishes a coordinated traffic strategy for the common intersection and merging conflicts of unmanned truck trucks in open pit coalmines, A multi-agent system simulation platform was built to evaluate the coordinated traffic efficiency under different initial average gap sizes of vehicles, with intersection traffic density, vehicle speed, and gap changes as key indicators. The results show that under the simulation conditions of this article, when the initial average gap of vehicles reaches three (four) times or more of the safe distance, the coordinated traffic performance of intersection conflicts (merging conflicts) is better, and the traffic capacity of intersections is close to the traffic capacity without conflicts.

Sep 1, 2024

By C. H. Wilson, J. W. Daly, J. J. Jakosky

Meteor Crater, Arizona, is a natural wonder which for years has been the subject of considerable discussion and study as to its origin and age (Fig. 1). Of the various theories advanced regarding the origin, two have been considered as most probable by a majority of investigators. The first theory is that the crater was formed by a meteorite or a swarm of meteoric material striking the earth at a high velocity and burying itself. The second theory is that the crater was formed by a "steam explosion" from hot solutions or gases coming from underneath the present sedimentary beds which overlie the area. In order to obtain more detailed information regarding the conditions existing at the crater, the present management decided to have a detailed geophysical examination made. The origin of the crater is of considerable scientific importance and interest. More or less active mining operations have been carried out during the past 20 years by various groups who believed that the crater was of meteoric origin, and who hoped that sufficient quantities of such material had been buried to be commercially valuable. Fragments of meteoric material found on the surface of the ground in the debris around the rim gave analysis of approximately 92 per cent iron and 8 per cent nickel, with some platinum and iridium. The material having a gross value of approximately $50 per ton, mining would be commercially profitable if sufficient quantities of the material existed in condition for mining. In the early work numerous drill holes and shallow shafts were put down, mainly in the northern portion of the crater. Pulverized material and debris caused considerable difficulty, and in an effort to overcome this the present management started a 1500-ft., two-compartment shaft on the south rim of the crater and outside of the fill zone. The intention was to sink the shaft in the solid rock outside of the crater, and then to crosscut toward the crater at a depth of 1500 ft. The work was finally stopped when a depth of 650 ft. was reached, because water poured into the shaft through large cracks and fissures in the rock. The enormous force responsible for the crater had also broken

Jan 1, 1932

By J. W. Miller

An investigation was begun by the Bureau of Mines in 1948 to determine the preparation characteristics of American coals. Results of the investigation were planned to be reported on a county basis and, from the data developed, to determine: (a) Which coals, either as mined or after beneficiation by conventional preparation, are suitable chemically under present standards for producing metallurgical coke. (b) Which coals require special and more intensive treatment in preparation than is now practiced. (c) Which coals cannot be considered potential sources of metallurgical coke, regardless of preparation. This report is one in a county series and describes the preparation characteristics of the coals of Logan County, W. Va. According to present-day standards for metallurgical coal, many believe that the sulfur content of the coal should not exceed 1.25 percent? Coal with more than this amount has been used for making metallurgical coke, especially when blended with coal containing less sulfur. In this series of reports 1.25 percent sulfur is used as a gage to determine whether or not a coal will be suited for metallurgical coke.

Jan 1, 1957

By Zay Jeffries

Tungsten has the highest melting point of all the known metals, namely 3350 C.; it is one of the hardest of the metals; it has the highest equiaxing or recrystallization temperature after strain hardening, of any pure metal known. It is particularly distinguished because, when composed of small equiaxed grains, it is extremely brittle and fragile at room temperature, and when possessing a fibrous structure it may be ductile and pliable at room temperature. The common ductile metals act in exactly the opposite manner in this respect. The present paper will include a brief note regarding the manufacture of wrought and ductile tungsten. The metallography of wrought and ductile tungsten in the various stages of manufacture will be considered more or less in detail. The general relationships between the properties of tungsten and other metals will also be considered. A discussion will be given explaining why fibrous tungsten is ductile at room temperature, even though past experience with other metals would indicate that it should be brittle. Finally, a brief note regarding some new fundamental metallographic propositions relating to all metals will be given. Manufacture of Wrought and Ductile Tungsten Up to about 10 years ago, it had not been possible to work tungsten mechanically. About the year 1908, Dr. William D. Coolidge, of the General Electrie Go., produced ductile tungsten from what was then supposed to be an inherently brittle metal and which, in fact, was inherently brittle in its normal state, that is, when composed of equiaxed grains. Since that time many products, chief among which are the filaments for electric incandescent lamps, have been made from wrought and ductile tungsten. Tungsten is produced chiefly from the minerals wolframite and scheelite.1-8 The ores may be reduced in many ways. For example, the ore may be fused with alkali carbonates and the fusion dissolved in water; sodium tungstate is formed, which is soluble in water. This

Jan 1, 1919

By M. J. Raffaldi, K. W. Harris, K. A. Perry

"Highwall miners have been widely used to extract additional coal reserves from existing surface operations, particularly on contour operations in the Appalachian coalfields. Using a continuous miner cutting head, coal may be extracted from significant depths (such as 150 m), leaving behind an array of web and barrier pillars with the purpose of maintaining highwall stability. This method inherently involves elevated risks to both equipment and personnel due to proximity to and increased exposure time near highwalls. As a result, modern operations should actively design web and barrier pillars to maximize extraction while providing adequate stability. The ARMPS-HWM software, an empirical-based program created for the design of web and barrier pillars at highwall mining operations, is one such approach. The calculated stability factor is compared with empirically established guidelines produced from examining case histories.The ARMPS-HWM program is a handy tool for initial design, but understanding the site’s structurally significant geologic features and geomechanical behavior is important and may potentially increase extraction. We created a two-dimensional numerical model using FLAC3D and calibrated it to ensure pillar strength, closely following the Mark- Bieniawski formula for a typical range of pillar geometries and overburden properties. The development of pillar stresses along a highwall panel was then numerically investigated as mining progressed, and the stress distribution between barrier pillars was found to be asymmetric, which can result in an over-design of the closeout web pillars if tributary area loading is assumed. Finally, the importance of adequate barrier pillar stability is highlighted."

Jan 1, 2014

By Frederick J. Browne

Water, water everywhere, but not a drop (fit) to drink! Trite, but how often only too true? What is there met with in mining which, under various circumstances, may be said to be the most sought-for and highly-prized and also the most objectionable and most feared? Water! What visions that combination of five letters brings to all thoughtful minds? Up to near the end of the eighteenth century water was thought lo be an element but was then discovered to be the result of the combustion of two volumes of hydrogen with one volume of oxygen, and water so produced is chemically pure. Pure water is a clear and colourless liquid when seen under ordinary conditions, but appears bluish when seen through a long tube, and this same bluish tint may be observed in many lakes, especially those of glacial origin. A story often told describes a prospector in the desert who, failing to find water to replenish his canteen, suffers torture and death under fearful circumstances. Then again we may recall the flooding of mines, where water poured in so quickly that there was no opportunity of saving the unfortunate workmen. Instances might be multiplied without number showing that either the lack or excess of this essential fluid has taken heavy toll of human life. In all branches of mining and associated industries water must be dealt with to a larger extent, from an economic point of view, than any other substance, and very often the purity of the water is a matter of considerable importance.

Jan 1, 1925

By James A. West

The Quapaw pool is one of the smaller pools in an extensive area of Bartlesville-sand production in the eastern part of Osage County, Okla. (fig. 1). Most of the fields in this area were discovered from 1906 to 1916 and were developed and operated similarly. The Quapaw pool is representative of the area, and much of the developed in studying this pool is applicable to the other reservoirs. This petroleum-engineering study of the Quapaw pool was conducted to provide reservoir data that may aid in more widespread application of the intensive secondary-recovery production methods that have been employed with excellent results in the Bartlesville-sand fields of nearby Washington, Nowata, and Rogers Counties. This study is particularly appropriate because of the intense interest in Osage County fields as areas suitable for water flooding. Water flooding was introduced first into Oklahoma during 1931 in Rogers County, and activity was concentrated in the shallow Bartlesville-sand fields of and Nowata Counties for many years. Although water-flooding projects are now operating throughout the State, the intense activity of the Nowata-Rogers Counties area spread to adjoining counties only during the past few years. Since 1948 the rate of oil production in Washington County (between Nowata and Osage Counties) has increased by 260 percent as a result of water flooding. Currently, leases in eastern Osage County are sought eagerly by water-flood operators, and during the past 2 years the Osage Indian Agency has issued nine permits for water-flooding projects in eastern Osage County. Water-flooding operations are in progress on several projects. Although large oil reserves in eastern Osage County should, be recoverable by water flooding, development and operation of projects will be more expensive than projects in the shallower producing areas to the east. In addition, the Osage County reservoirs appear to be more complex and somewhat more difficult to water-flood successfully. It is hoped that this study will contribute to better understanding of the Quapaw reservoir and, in a general way, to the many similar reservoirs in eastern Osage County.

Jan 1, 1952

By John Newby, Ulf Gwildis, Ken Massé, Guillaume Roux

How to connect an effluent conveyance tunnel to riser shaft and diffuser arms of an outfall system is dictated by the ground conditions, which ideally include rock or soil strata of low permeability. Where such favorable conditions are beyond reach, both the complexity of designing and the risk of constructing this crucial system connection increase disproportionally. This paper describes the considerations that went into the approach of connecting a 5-m-diameter TBM drive with the in-river riser shaft of the Annacis Island WWTP New Outfall System in the highly permeable Fraser River sands at hydrostatic pressures exceeding 3 bar.

Jun 23, 2024