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By Paul Saxton

INTRODUCTION AND SUMMARY This short paper deals with the history of the Nickel Plate Mine from 1898 to 1987, with the major focus on the time period 1984 to 1987. Operations from 1898 to 1955 are reviewed in a cursory manner with the emphasis on some interesting points in the early 20th century. A review of the major exploration work carried out in 1984 to 1987 is presented and the process of moving the project through feasibility, government permitting and construction is described. The Hedley gold camp is situated approximately 40 kilometres east-southeast of Princeton, in southern British Columbia. The area has had a long history of gold mining and between 1902 and 1955 approximately 1.5 million ounces of gold were won from several mineralized skarn orebodies. Most production came from the Nickel Plate and Hedley Mascot mines. AN EARLY TO MID 20TH CENTURY SUMMARY The Nickel Plate is one of the oldest mines in the province. The mine had operated from 1904 to 1930 and, after a period of shutdown, from 1934 to 1955. The mine was revived in 1967 for exploration and. will resume production during the first half of 1987. In the first period the Yale Mining Company and Daly Reduction Company operated for six years and Hedley Gold Mining Company for twenty-one. In the second period the mine was operated by the Kelowna Exploration Company Limited and Kelowna Mines Hedley Limited for twenty-one years. In the present period the mine has been revived by Mascot Gold Mines Limited.

Jan 1, 1987

By J. Alton Burks, Roy C. Bartholomae

The chain conveyor is utilized extensively in underground mining to convey raw ore, especially coal. It is estimated that several thousand loading and continuous mining machines rely on this type of conveyance. Although the chain conveyor is both efficient and highly reliable, its use is generally associated with the production of noise levels that often exceed 105 dBA at the operator's position. Thus, it is one of the most significant contributors to the occupational noise problem experienced by miners in the underground coal mining environment. Conventional engineering noise controls that result in an average reduction of 4 dBA have been previously designed and implemented. However, a novel solution involving a change in conveyor operation has been proposed that takes advantage of two aspects of conveyor noise: 1) conveyor noise has an approximately cubic dependence on conveyor chain speed and 2) due to the damping provided by coal, a full conveyor is 5 dBA quieter than an empty one. An engineering analysis has shown that a significant reduction in the operating noise level of a typical continuous miner can be achieved through the use of an adjustable speed drive automatically controlled by a coal loading sensor that maintains a full conveyor at all times. The potential reduction depends primarily on the mining conditions (coal seam thickness and the presence of either rock or water) and varies from 7-18 dBA. Other benefits to be derived from the use of a variable speed drive include reductions in power consumption, dust, and maintenance costs.

Jan 1, 1992

By F. Grandjacques

INTRODUCTION Selective Reduction of Nickel in Oxidized Ores Oxidized nickel ores, either garnieritic or lateritic, contain much more iron than nickel. The regular carbon reduction in an electric furnace is operated in such a manner that the greater part of iron oxides is reduced simultaneously with nickel oxide, resulting in a low nickel content ferronickel. In order that the nickel content of residual slag may be suitably low, -excess carbon must be fed so that the carbon content of the ferronickel thus obtained is that of casting iron. The metal also contains other impurities such as silicon, chrome, etc. In order to convert the casting iron into slightly carburized ferronickel with high nickel content, the greater part of the carbon and more than half the iron contained therein must be oxidized by means of oxygen. Energy is thus consumed as carbon, and power to reduce iron oxides, and more energy is consumed as oxygen to re-oxidize the iron contained. This method can be economically adopted for nickel ores with grades ranging around 2. 5 to 370, but it gets excessively costly when nickel grade falls below these values. This is why, for nickel ores with low nickel grades and high iron content, studies were conducted to develop a selective reduction process which, while reducing only a small part of the iron oxide, would provide efficient reduction of nickel oxide. Rich ferronickel is thereby obtained, with nickel content ranging around 30 to 50%. Due to the presence of slag with a high iron oxide content, the metal thus

Jan 1, 1979

By Eckart Schneider

PROJECT The Walgautunnel is the heart of a new hydro scheme in Western Austria, which is supposed to go into operation in 1984. With it's length of 21,4 km, a bored diameter of 6,25 m and an internal operating pressure of 13,5 bar it will be the largest water conducting tunnel in Austria. Even compared with some of the country's world-famous highway tunnels like 'Tauern' or 'Arlberg' it has to be regarded as a major tunneling project. Owner is the Vorarlberger Illwerke AG, a power corpo¬ration founded in 1924. In the course of the past 6o years this company developed the 'Werksgruppe Obere Ill - Lünersee', consisting of 6 major power plants and 4 large reservoirs. The installed capacity is 1.114 MW in the generating and 529 MW in the pumping mode. The total power output amounts to 1.916 GWh. The water for power generation comes from the glaciers of the Silvrettagroup, as this corner of the Austrian Alps between Vorarlberg , Tyrol and Switzerland is called. The Walgauwerk utilises all the water accumulated by the existing schemes as well as the so far unused run-off water, passing by in the river Ill. The intake to the Walgau-Tunnel is situated right beside the lower reservoir of the recently completed pump-storage plant 'Rodund II' at an elevation of 64o m above sea level. Though the head is a mere 162 m, 1 billion m3 of water will generate 356 GWh per annum. The power-output of the two Francis turbines is 86 MW.

Jan 1, 1983

By S. R. Wardwell, M. J. Robison

INTRODUCTION The first phase of the Los Angeles Metro Rail Project consists of 7.1 km of subway and stations running through downtown Los Angeles from Union Station to MacArthur Park. Contract A146, Tunnels from 5th/HILL Station to 7th/Flower Station, involves tunnel construction through the heart of downtown Los Angeles. The alignment of the tunnels passes beneath twelve buildings, ranging from a 3-story below grade parking structure to numerous 12 to 14 story buildings. The soil along the alignment is alluvium, consisting of silts and clays, clean sands and gravels located above the ground water table. Because of unstable ground conditions, which led to excessive ground losses in several instances, and because of the potential for excessive building settlements, it became necessary to design and perform a program of chemical grouting. The chemical grouting program was designed such that tunneling could proceed on a one shift per day basis, with chemical grounting being performed on the remaining two shifts. Each day 21,000 to 31,000 liters of sodium silicate grout were injected through sleeveport grout pipes installed 18 m deep through the tunnel face. Tunnel advance rates of 12 m per day, 60 m per week, under full chemical grout cover were achieved. The chemical grouting program virtually eliminated both ground loss and settlement and permitted successful excavation of the tunnels. The purpose of this paper is to describe the chemical grouting program used to control ground losses and settlement on Los Angeles Metro Rail Contract A146. The paper begins with a description of

Jan 1, 1991

By Cyril Smith

IN the study of the structure or the properties of a series of alloys or nonmetallic compounds, it is often advantageous to express the com-position not as percentage by weight, according to which the material is always made up and analyzed, but as the atomic percentage of the two constituents. The conversion from the one to the other is repre-sented by the formulas: 100A 100x or 1 x/A+100-x/B B(100-x) _ 100yA 100y [2] X. yA + (100 - y)B or y (100 - y) where x and y are the weight and atomic percentages respectively of the element of atomic weight A, and (100 - x) and (100 - y) are the per-centages by weight and by atoms respectively of the element of atomic weight B. While calculations according to these formulas are simple, they are time consuming if several conversions have to be made. In 1931 Water-man1 constructed a nomograph for performing the conversion, but this did not permit an accuracy greater than about 1 per cent to be obtained in the neighborhood of 50 per cent. Ölander2 has proposed a graphic method simpler than Waterman's and one that gives a uniform precision throughout the entire scale. The possible accuracy is about 0.5 per cent of the whole, depending on the size and accuracy of the coordinate paper used. Recently, Hermann3 has described a slide rule for making the calculations. These devices make use of the simple rearranged equation

Jan 1, 1933

By T. Ono, B. Altansukh, S. Kawamura, K. Haga, A. Shibayama, Y. Takasaki

In recent years, the grade of silica in zinc concentrate has increased due to the degradation of zinc content and the increase in impurity content in natural ores. It implies that the development of silica removal technology from zinc concentrate is necessary to solve problems in the smelting process caused by the high content of silica in zinc concentrate. In this paper, the authors investigated the silica removal processes from silica-rich zinc concentrate by mineral processing approaches such as re-grinding and flotation. This study focused on the pulverisation process as a pretreatment for the investigation of individual minerals' liberation from the silica-rich zinc concentrates using different kinds of pulverisers. Flotation experiments were performed to separate silica and zinc concentrate from the pulverizsd feed sample using a pH regulator (NaOH), activator (CuSO4), collecting agent (PAX), and foaming agent (DOW froth 250). Results showed that the liberation rate of silica (SiO2) was reached 75% from 13% by pulverisation in an attritor with a 2 mm ball in diameter, while silica accumulated in a fraction over 20 mm in size. Flotation experiments indicated that silica removal efficiency was achieved by 44% from + 20 mm fraction obtained from pulverisation whereas the grade of silica in froth reached 1.85 mass% from 4.5 mass%. Results indicate that silica could selectively separate from silica-rich zinc concentrate, and 99.8 % zinc recovery is achieved under the studied conditions. Keywords: Zinc concentrate, silica, pulverisation, liberation, sieving, flotation

Jan 1, 2020

By M S. El Salmawy

In order to develop the HF-free flotation reagent system, the main objective of this investigation was to study the possibility of separation of quartz from feldspar using non-ionic surfactants as the collector. The non-ionic surfactants used were polyoxyethyl cethyl ether (PECE) and polyethylene glycol monocethyl ether (PGME). The flotation behaviour of quartz and microcline with PECE and PGME was investigated. Each surfactant was a good selective collector for quartz with its recovery being influenced by pH and surfactant concentration. Quartz is floated favourably by both types of polyoxyethylene non-ionic surfactant whereas microcline was not so much. The floatability of quartz increases as the oxyethylene length of surfactants increases. Zeta potential measurements in the system of PGME/mineral were also carried out. It was determined that in the absence of PGME the points of zero charge for quartz and microcline should be approximately at pH 2.5 and 1.8, respectively. The addition of PGME to the system causes both minerals to become less negatively charged. Differences in the zeta potential value between quartz and microcline, in the presence of PGME, were detected. It can be suggested that the interaction of the oxyethylene group to the microcline surface should not be as strong as that to the quartz surface. In the mixed surfactant system of PGME and dodecylamine acetate (DAA), a small addition of DAA causes drastic enhancement of quartz flotation in the wide pH range of 1 ~ 10. In the mixed surfactant system selective flotation of quartz from microcline would be anticipated at pH

Jan 1, 2005

By P Marlow

Raiseboring is an attractive method of constructing shafts, being safe, fast and comparatively cheap. But this means back-reaming through weathered ground. However in the gravels and weathered near-surface rocks typical of the Western Australian goldfields, back reaming large diameter shafts through to the surface is risky and conventional sinking from surface has normally been required.An alternative construction approach has recently been used to stabilise the weak surficial materials and allow raiseboring through to the surface. The method is based on first installing rings of non-contiguous reinforced bored piles around the shaft perimeter, for temporary support, then back reaming shafts at full diameter through to the surface. Immediately after the reaming head is removed, the weak exposed materials are supported using remotely sprayed fibrecrete.The method has been successfully applied to four shafts since July 2007; 3 m and 4 m diameter shafts at Trident Mine, a 3 m diameter shaft at Wattle Dam and a 4.5 m diameter shaft at Athena Mine.Bored pile layout designs have varied from eight to 24 piles, of diameters 120 to 270 mm, in one or two rings. In one case, the top 10 m of the proposed shaft was pregrouted. Subsequent surveys have confirmed that fallout occurred in some shafts, out to the ring of piles, implying that the piles inhibited collapse.The practical implementation of the method was not always easy and many valuable lessons have been learnt. This paper documents key aspects of the method and the critical elements for its application.

Mar 21, 2011

By Rasool Hejazi

The feed to Chadurmalu iron ore concentrator plant is a mixture of magnetite and haematite iron ore with a Fe/FeO ratio of about 8. The feed to plant, after grinding via wet SAG mill, is pre-separated by wet low intensity magnetic separator. Magnetic product is conducted to magnetite processing circuit for producing magnetite concentrate, and nonmagnetic product is directed to haematite processing circuit. Due to surface oxidization of magnetite particles and a decrease in magnetic attraction properties, significant amount of these particles are misled to tailing which results in decreasing the efficiency of haematite processing circuit. This problem can be remedied by using magnetic drum separator with more magnetic intensity and/or gradient. In this paper, the replacement of LIMS separators with wet medium intensity magnetic separators with a field intensity of 3800 gauss on drum surface (MIMS) have been suggested and considered as the most suitable solution to prevent the loss of magnetite particles. The results of carried out investigations with replacement of drum separators in industrial scale, showed that utilizing MIMS in magnetite processing circuit resulted in increasing final concentrate weight recovery on average by 2.59%, without any adverse effect on the concentrate quality; decreasing the magnetite content in the feed to high gradient magnetic separator (HGMS) by about 3.5%; decreasing the feed to floatation part by about 7% and consequently decreasing consumption of chemical reagents; increasing Fe/FeO ratio of the feed to plant. Keywords: iron ore, medium intensity magnetic separator, haematite, Chadurmalu

Sep 1, 2012

By Marcos Paulo Kohler Caldas

O desenvolvendo da indústria de eletroeletrônicos associada ao barateamento dos produtos tem reduzido a vida útil de equipamentos levando a uma geração elevada de resíduos de equipamentos eletroeletrônicos (REEE). Um componente desse resíduo são as placas de circuito impresso, que possuem em sua composição altos teores de metais, que podem ser recuperados através de processos de reciclagem. O presente trabalho busca caracterizar placas mãe de computador, determinando sua quantidade de material orgânico, cerâmico e metálico. As placas foram direcionadas para cominuição, que foi realizada em moinho de facas com grelha de 9mm, seguida por um moinho de martelos, atingindo uma granulometria menor que 2mm. A amostra foi então quarteada, para uma maior homogeneização e passou por ensaio de digestão em água régia. O licor resultante foi diluído para determinação do teor dos metais Ag, Al, Au, Ba, Ca, Cu, Fe, Ni, Pb, Sn, e Zn utilizando espectrometria de emissão óptica por indução de plasma (ICP-OES). O sólido filtrado, também resultante da digestão em água régia, passou por um ensaio de perda ao fogo a 800°C por uma hora, para determinar o teor de material orgânico. Os resultados indicaram que o Cu é o metal de maior concentração com 22,5% na placa de circuito impresso e que a mesma possui 43,7% de metais, 31,9% de polímeros e 24,4% de cerâmicas. A prata representa 0,04% dos metais e sua obtenção será realizada na forma de nanopartículas a partir de rotas hidrometalúrgicas.

Aug 8, 2018

By Leiliane Alves de Oliveira

O aço EUROFER (9Cr – 1W), pode ser utilizado em turbinas para geração de energia, vasos de pressão, reatores nuclear ou aplicações, onde o material é submetido a temperaturas de serviço entre 250°C e 450°C. Uma forma de melhorar as propriedades do aço, para que ele trabalhe a temperaturas mais altas ou que se torne mais estável é adicionar partículas de segunda fase na sua matriz. Estas partículas podem estar na forma de óxidos, carbetos, nitretos ou até mesmo em solução sólida quando alguns elementos químicos são adicionados ao material. Neste contexto, este trabalho objetiva estudar o efeito da adição de 3% de carbeto de tântalo na matriz metálica do aço ferrítico/martensítico. Para isto a metalurgia do pó foi a rota empregada para a produção deste compósito de matriz metálica (CMM). Duas moagens distintas foram realizadas. A primeira com o aço EUROFER e a segunda com o aço EUROFER com adição de 3% de carbeto de tântalo (TaC). A moagem de alta energia foi realizada durante 5 horas. Em seguida, os dois pós produzidos foram sinterizados em um forno a vácuo (10-4torr) a temperatura de 1.250°C durante 60 minutos. O produto final foi caracterizado por microscopia óptica, microscopia eletrônica de varredura (EDS) e ensaio de microdureza. Os estudos iniciais dos sinterizados obteve uma resposta positiva nas propriedades mecânicas independente do processamento. Com valores de microdureza maior que 100% do valor de 333,2 HV obtidos para o aço puro como recebido(barra).

Aug 8, 2018

By L Vimercati, R Williams

Transitioning to a green future requires the mining industry to adopt sustainable practices. Filtered tailings are become a key expectation of the communities we operate in and are growing in a number or mining commodities including bauxite, nickel, gold and iron ore. The filtration technologies required range from dewatering screens to vacuum and pressure filters. Particular challenges faced in iron ore applications include large scale which means several units of large size are often required. In addition, a high specific gravity that cause sedimentation issues and a high abrasion level make demands on achieving reliability level at above 90 per cent. This paper describes the testing, selection criteria and specific features required to provide a rational option for equipment and plant design. An example of how this has been applied in an iron ore application in Brazil is used to demonstrate a successful outcome. This project installed four overhead beam filter presses each producing around 200 t/hr utilising a recessed chamber plate, feed pressures up to 15 bar, cake thickness of 5 mm. The moisture lower than 20 per cent that was produced was considered to provide material with handling and geotechnical properties to guarantee a safe stacking. Regular high pressure washing at 100 bar was considered imperative to maintain cloth life and process performance. The correct management of the system (OPEX control) by PLC control ensures a balance between machine potentials and plant needs. With this equilibrium it is possible to limit mechanical wear preserving equipment lifetime.

Sep 18, 2023

By J Safarian, M K. Kar

Bauxite residue is one of the most important by-products from the alumina industry with no commercial use till now. The utilisation of bauxite residue through pelletising with different lime additions, hydrogen reduction, and smelting has been studied in this work. Three different types of green pellets were made with varying calcite-to-bauxite residue ratio and subsequently sintered at elevated temperatures. The sintered pellets were isothermally reduced at 1000°C under hydrogen gas followed by smelting of the reduced pellets in argon at 1500°C. Smelting of the reduced pellets leads to the recovery of metallic iron and the formation of a leachable calcium aluminate slag. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterise the phases and microstructural analysis. The iron produced in the smelting process has a high purity, above 99.5 wt per cent. While the iron content of the slags is quite low, and the slags shows variations of krotite (CaAl2O4), gehlenite (Ca2Al2SiO7), and perovskite (CaTiO3) phases based on the variation of calcite addition. It was found that the more calcite addition in pelletising yields higher percentage of krotite phase as compared to lower calcite-containing pellets. Employing quantitative XRD analysis, the krotite phase fraction was found approximately 85 wt per cent for higher calcite-added pellet, and around 74 wt per cent for lower calcite-added pellet. FactSage™, ver 8.1 (Thermfact and GGTTechnologies) thermodynamic software was used to evaluate the obtained experimental data, they both revealed that the

Jun 19, 2024

By K. Tada

A surface of a magnesium slab (hereinafter, referred to as Mg slab) or magnesium alloy slab (hereinafter, referred to as Mg alloy slab) becomes black with the use of conventional manufacturing methods. The methods also involve a danger that an explosion of the molten magnesium occurs through contact with cooling water. Thus, it has been impossible to produce a slab having a smooth surface. In the present method, a molten magnesium alloy is supplied into a mold, which is sheltered from the surroundings, from a pool in tundish, which is shielded from the surroundings. AZ31B slab formed in the mold is drawn horizontally out to the outside from an outlet of the mold by revolving of the pinch rolls. A cooling water is jetted at an acute angle onto the slab on the outer side of the mold outlet. Further, an inert gas is sprayed at the inner side of the mold outlet in order to seal in a gap between a free surface of the molten magnesium alloy and a sheltered board surrounding an upper surface of the mold. As a result, oxygen and droplets of the cooling water are prevented from running back to the mold side through the gap. AZ31B slab has a smooth surface condition and high quality without a gas porosity, a segregation or the like. Further, the slab has a size of a width of 100 to 120 mm, a thickness of 5 to 20 mm and a span of 10 m or more.

Jan 1, 2006

By S. Cotten

The concept for a Mine Escape Vehicle (MEV) is motivated by the desire to enable personnel to evacuate a mine rapidly as the first and most desirable response to any underground emergency. Under a NIOSH contract, Raytheon UTD developed a conceptual design for a vehicle that coal miners could use to facilitate their rapid exit from an underground coal mine in the case of emergency, including fire or explosion. The vehicle requirements include the capacity to provide life support functions for a number of miners, operate in an oxygen deficient, low or no visibility atmosphere, and travel at speeds faster than miners can walk out of the mine. To develop the MEV concept, three primary tasks were identified and executed. The first task focused on developing a realistic concept of operations (CONOPS) and associated high level vehicle requirements. The second task identified and evaluated currently available equipment and technologies that could be applied to address the CONOPS. The final task developed a design concept that integrated the identified components for the five (5) MEV sub-systems to provide the foundation for future detailed engineering design and prototype construction. The resulting MEV design concept is centered upon retrofitting existing mine personnel carrier chasses with available, mine-worthy equipment capable of addressing the MEV requirements. This approach offers a practical and economic avenue to prototype development and delivery with minimum lead-time and risk. Furthermore, by integrating familiar and available equipment into the design and CONOPS, the resulting Mine Escape Vehicles should also be more readily accepted by the mining industry.

Jan 1, 2010

Works Manager or General Superintendent.-Technical graduate, for position with a company whose works consist of a large machine shop and foundry. This company manufactures well-known power plant equipment. Location, Pennsylvania. Salary, $5000-$8000 per year. R-871. Motion Study Engineer with extensive experience in shop operation and motion study. Must have sufficient technical experience to recognize inefficiency and waste in plant. Salary, $175-$200 per month. Location, New Jersey. R-876. Metallurgical Engineer.-Technical graduate with at least 2 or 3 years' practical experience in the operation of zinc smelters. Duties will be to take charge, under the guidance of -the superintendent of the smelter, of the operating end of the furnaces, and the roasting kilns, as well as the mix room and ore crusher. Man desired should not be over 30 years of age and should be progressive and able to handle men. Salary, $250 per month. Location, Oklahoma. R-877. Private Secretary to Vice-president in charge of development department and laboratories of large manufacturing plant; must be technical man of good personality, and A-1 in every respect, as position is an important and responsible one. Location, Ohio. R-896. Sales. Engineer familiar with his local territory, particularly with the fanning trade. Should have had at least 2 years' experience in selling tractors; and in any event, must have had at least 5 years' experience in selling machinery. High grade, energetic, and capable; man who is not satisfied with less than $3000 per year and who can earn up to $7000. Location, Iowa. R-897.

Jan 8, 1919

By Michael H. Leon, John A. Organiscak

Controlling worker dust exposure on longwall mining systems is difficult because the working face area serves as an immediate return during the mining cycle and the amount of airborne dust generated is directly related to production. Since improvements in longwall mining technology have significantly boosted production levels, additional technology is needed to control the airborne respirable dust generated at present and future production levels. One concept to reduce longwall worker's dust exposure is to maintain two splits of air at the face -- a clean intake split in the workers walkway, and a return (dusty) split over the face conveyor. The U. S. Bureau of Mines has recently investigated a concept to overcome the visibility handicap of face partitions by utilizing a permeable polyester mesh. The mesh material was anticipated to provide adequate air-splitting capabilities as long as the pressure differential between the face and worker walkway was minimal. Initial testing of this concept at the Bureau's Lake Lynn Laboratory showed that notable reductions could be achieved with a 1/8 in (3.18 mm) and 1/16 in (1.59 mm) mesh opening size. Dust reductions at 100 ft (30.5 m) and 200 ft (61.0 m) downstream of source were 58 and 36 pct, respectively, for the 1/8 in mesh and 79 and 55 pct, respectively for the 1/16 in mesh. Longwall application of the 1/8 in mesh showed similar results to the Lake Lynn Laboratory tests. A flame retardant mesh was used underground with portable lighting mounted on the shearing machine for face side lighting.

Jan 1, 1993

AT THE dinner at the Cosmos Club in Washington, tendered to Herbert Hoover on Jan. 5, on the occasion of his retirement from the presidency of the Federated American Engineering Societies, he made an informal speech in which he pointed out not only the unique position which the engineer now occu-pies by virtue of the new Federated Societies but also the opportunity that is thus presented for national service. In this connection and in pointing out some of the reasons for the present economic maladjust-ment, Mr. Hoover said in part: This body has entered upon a path of public serv-ice that is unique in the whole United States. The engineer has devoted himself all these years to the upbuilding of the material values of the United States. He has done that effectively more effectively than-has been accomplished in any other of the great countries of the world. The birth of this society marks the evolution of the engineer into an interest in public affairs. With his intelligence, his experience and training and the unique knowledge that he possesses not only of the material but the intangible values among our people, he is now organized so that his united voice may become heard outside of his profession. We have probably 175,000 engineers in our country, representing an intellectual possibility for service possessed by no other group. It is therefore an augury of real social development when the engineers of the United States join together for purposes of public service.

Jan 3, 1922

By Gregg Sherry, Bob Gordan

INTRODUCTION This paper report presents the general case history for the construction of the North Outfall Replacement Sewer (NORS) project. A 1982 City of Los Angeles Wastewater Facilities Plan recognized that a 19.3 km (12¬mile) section of the North Outfall Sewer (NOS), from Culver City to the Hyperion Treatment Plant, was deteriorating and had insufficient capacity. Built in the 1920s of unreinforced concrete and lined with vitreous clay tiles, the originally unventilated NOS suffered considerable corrosion by H2S gas. This caused roof tile and concrete to fall to the bottom of the pipe, which, over the years, reduced the 11.9 M3/S (420 cubic feet per second (cfs)) design capacity of the NOS to a current level of approximately 8.5 M3/S (300 cfs). This worsening condition, thereby contributing to the polluting of Santa Monica Bay. This situation culminated in the State of California Regional Water Quality Control Board, Los Angeles Region, issuing a Cease and Desist Order on January 27, 1986, which required the City of Los Angeles to eliminate such dry weather overflows through a number of prescribed actions. One of these was to construct the North Outfall Replacement Sewer (NORS) by April 1, 1993. PROJECT DESCRIPTION The NORS Project involved the construction of over eight miles of tunnel and related structures. It consisted of a main tunnel conduit to convey sewage to the Hyperion Treatment Plant and four diversion lines connecting the main tunnel to major existing

Jan 1, 1993