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By Bertram Price

Libby, Montana is the site of a large vermiculite deposit that was mined between 1920 and 1990 to extract vermiculite for commercial applications such as insulation, gardening products, and construction materials. The Libby vermiculite deposit also contains amphibole minerals including tremolite, actinolite, richterite, and winchite. Historically, Libby mine workers experienced high exposures to amphibole structures, and, as a group, have experienced the health consequences of those occupational exposures. It has been suggested that Libby residents also have been and continue to be exposed to amphibole structures released during the vermiculite mining operations and therefore are at increased risk for disease. The Agency for Toxic Substance and Disease Registry (ATSDR) conducted two epidemiological-type studies of residents living in Libby and the surrounding areas to assess these risks. The Environmental Protection Agency (EPA) collected and analyzed exposure data in Libby and used those data to project risks of asbestos-associated disease for Libby residents. The EPA has placed the Libby Asbestos Site, which includes the mine and the town of Libby, on its National Priority List of hazardous waste sites in need of clean up. This article presents a review of the exposure studies conducted in Libby and an analysis of health risks based on the data collected in those studies. Libby mine workers have experienced elevated levels of asbestos-associated disease as a consequence of their occupational exposures to amphibole structures. Libby residents? exposures typically are substantially lower than mine workers? historical exposures, and the health risk projections for residents are, accordingly, substantially lower. © 2007 Published by Elsevier Inc. Keywords: Libby; Montana; Vermiculite; Amphibole minerals; Asbestos; Asbestos-associated disease

Jan 1, 2007

By D. A. Trotter, G. J. Goddard

"This paper describes a method of deciding on various design parameters for a sublevel caving layout. Layout design curves are obtained from the output of a computer optimization program. The program uses mathematical relationships derived from the theory of gravity flow of material to optimize the large number of interdependent design variables which are involved.IntroductionIn the design of an efficient sublevel caving mining system, a large number of interrelated variables need to be considered. Although many papers discuss individual variables, very little exists in the literature to show how these variables interact to achieve optimum results. This can lead to trial and error in sublevel caving design, which can prove costly, particularly because sublevel caving is a mining method which requires integration with sublevels above and below. With no pillars being left, experimental stopes cannot be isolated for study. Unfortunately, the complexity of layout design and the costs associated with trial and error have caused many planning engineers to choose more tried and tested mining methods.Sublevel caving works best to extract low-value ore surrounded by incompetent rock. All phases of the mining method can be highly mechanized, allowing low operating costs and high production rates. Good safety records are achieved, as workers are always in 'good' ground and the method is regular, making it comparable to an industrial process."

Jan 1, 1981

By Tiziana Apuani

The study refers to an area of about 70 km2, extended in the Italian Central Alps along the the San Giacomo Valley where different civil and mining works are present The regional geological setting is related to the Pennidic Nappe arrangement, characterized by the emplacement of sub-horizontal gneissic bodies resulting from the Mesoalpine isoclinalic folding of crystalline basements, emplaced throw East, and separated by matasedimentary cover units. The investigated geological rocks, belong to the ?Tambò?Unit, overlapped by its meta-sedimentary cover and by the ?Suretta? Unit. The tectonic contact gently dips to the E?NE. The valley, furrowed by the Liro Torrent, follows a N?S striking tectonic lineament, almost parallel to the nappe contact. A number of more then 70 sites, distributed in the studied area, were chosen and detailed structural and geomechanical field surveys were performed to characterize the rock masses, its intact rock and discontinuities. The procedure identifies the number of joint sets, their representative orientation, the set spacing, the type of movement, the amount of dilatation, the degree of alteration, the roughness coefficient, the presence and nature of infill. Rock mass quality indexes, such as the Rock Mass Rating (Bieniawski, 1989) or the Geological Strength Index (Hoek et al. 2002) have been evaluated in each surveyed site. The work is a contribute in assessing how the geometrical and geomechanical properties of the rock masses can be regarded as regionalized variables. The spatial distribution of these properties is a function of the geological and structural phenomena at which the rock masses have been subjected. The presented geostatistical analysis regards the spatial variation of the orientation of the most representative joint set.

May 1, 2009

By Scott Rosenthal, David Gilkey, Michael McGivern, Lorri Birkenbuel, Daniel Autenrieth, Ty Murphy, Hadi Aldossari

A safety climate case study was carried out at a surface metal mine where investigators administered the Liberty Mutual Short Scale Safety Climate Survey to 365–368 miners to measure safety climate in consecutive years. Following the baseline safety climate survey in 2019, Foundations for Safety Leadership (FSL) training was conducted with 81 middle to upper management employees at the mine site. Investigators found statistically significant differences in the pre vs. posttraining FSL assessment scores of the middle to upper management employees who attended the training. The follow-up safety climate evaluation was compared to baseline scores and revealed no significant improvement. The overall baseline company safety climate score of 76.38 increased minimally to 76.50 (p-value = 0.616). Investigators also evaluated differences in safety climate between the company’s three major divisions (operations, maintenance, and administration). Both years administration had the highest mean score and operations had the lowest mean score. The authors attributed the statistically significant differences found among the three major divisions to various dissimilarities in their work environments.

Aug 13, 2021

By Pierre Pelletier, Christian Pichetie, Dany Pelletier

"IntroductionDuring 1994, Barrick Gold Corporation, or American Barrick at that period, acquired Lac Minerals Ltd. properties. One of them was the Bousquet Complex. The Bousquet Complex is divided into three distinct sites: one mine (Bousquet 2), one mill (Est-Malartic Division) and one analytical chemistry laboratory (Les Terrains auriferes).The Bousquet 2 orebody was discovered in 1986. An extensive drilling program was initiated during 1987. Its purpose was to define the orebody extent. At the end of 1997, gold production from Bousquet 2 mine reached 1 290 000 oz of gold from a cumulative tonnage processed of 4 175 000 M t.From 1980 to 1990, the Est-Malartic mill was used for the treatment of ore from the following mines: Bousquet 1, Doyon, Francoeur (Richmont mines), Buckshot and 1-20 stope. At present, the mill receives ore from the Bousquet 2 mine.HistoryThe Est-Malartic mill is located close to the town of Malartic in northwestern Quebec. The mill has been in production since the mid-1930s processing mainly clean, free mill gold ore. Active mining from the Est-Malartic mine ceased in 1979 and the mill was switched to custom processing of ore from La Mine Doyon located some 45 km to the west. This custom processing arrangement continued until 1987 when the expanded mill at Doyon became available to process all of the Doyon production. In 1987, Lac Minerals commenced development of a second mine at the Bousquet site located 40 km west of Malartic. This mine, Bousquet 2, is the down dip extension of the La Ronde mine developed by Agnico Eagle. During pre-feasibility evaluations, it was determined that it would be economically more attractive to modify the existing Est-Malartic mill than building a new facility on site. The Est-Malartic mill modifications for processing the high-copper/gold ore from the Bousquet 2 mine began in late 1989 and new circuits were commissioned in mid-1990. Modifications included the addition of both gravity and flotation concentration circuits to recover coarse, free gold and the copper. The existing leaching circuit continued to operate on the copper flotation tailings with some minor modifications to the solution handling systems. A S02/Air cyanide destruction circuit was also added at that time."

Jan 1, 2000

INFACON conjures up many things for many people. For the fortunate few who have been actively involved with this event since its inception, it brings back memories of far places, stimulating debates and above all, the people who have over the years contributed to the outstanding success of the Congress and who have added to the wealth of knowledge on all aspects of ferroalloys. The International Ferroalloy Congress (INFACON) has been held every three years since 1974. INFACON X will be held in Cape Town in February 2004. Simple arithmetic shows that next year?s Congress should in fact be INFACON XI. Thus, one Congress was skipped. INFACON 74, as the name implies, was held in 1974, in Johannesburg, South Africa. The event was sponsored by the Ferro Alloy Producers? Association of South Africa (FAPA), the National Institute for Metallurgy (NIM - Mintek as it is known today) and the South African Institute of Mining and Metallurgy (SAIMM). You will see some of the same sponsors involved in INFACON X. Dr. Robbie Robinson, renowned academic and past president of the SAIMM, was the Chairman of the Organising Committee. The editor was Dr. Helen Glen. Anyone fortunate enough to possess a copy of the proceedings of this first Congress will agree that from a literary and technical perspective, it is still the benchmark for subsequent events. A unique feature of INFACON 74 was the use of rapporteurs (my first duty) to ensure that the discussions following the presentations were recorded (in direct speech) as accurately as possible. This involved time-consuming correspondence (can you imagine life before e-mail?) to all parts of the world between the author and the person posing the question, with the rapporteurs acting as go-betweens. It is understandable that the much-awaited proceedings only saw the light in 1975. The names recorded in the proceedings as the members of all six committees read like the who?s-who of the South African ferroalloy industry at the time: Dr. Peter Jochens, Mr. Harvey Reid, Mr. Piet Streicher, Prof David Howat, Mr. Sigurd Selmer-Olsen - to name but a few. The Congress was held in the new, very fashionable and upmarket Carlton Hotel in the CBD. In the Foreword of the proceedings, Dr. Robinson provides an insight into the event. Three hundred and thirty six delegates from twenty two countries attended the Congress, which was opened by the Honourable P.G.J. Koornhof, Minister of Mines. Again, the opening address makes fascinating reading. During the Congress an ad hoc committee was convened as the first International Committee on the Organisation of Ferroalloys Congresses, with representation from the main ferroalloy associations of the world. The following decisions were recorded: ? The Congress would be continued at three-yearly intervals under the name of INFACON ? Every third Congress would be held in South Africa ? NIM (Mintek) would provide the permanent secretariat. Six technical sessions were held, each preceded by a plenary address with a closing address by the session chairman. In all, thirty technical papers were presented. Prior to the closing address, a panel discussion on factors affecting the future of the ferrochromium industry provided stimulating debate in the form of a question-and-answer session. The hosting country for the next INFACON would be announced. Eventually, word got round that the next INFACON would be held in Japan. However, due to unforeseen circumstances, the event was cancelled ? thus no INFACON 77. INFACON 80 was subsequently held in Lausanne, Switzerland from 12th to 16th October 1980. The event was organised by IFPEO, Institut des Producteurs de Ferro-Alliages d?Europe Occidentale. The Congress was officially opened by the President of IPFEO, Mr. R. Björklund, who was also President of the Organising Committee. The technical sessions were held in the Palais de Beaulieu. The Congress was well attended by 400 participants from 28 countries as well as 100 accompanying ladies. A total of four plenary addresses and 18 technical papers were presented. As with the first event, an international panel discussion (questions and answers) preceded the closing address. In his closing address, Dr. Louw Alberts, Chairman of the International Committee on Ferroalloys and President of NIM, presented an insight into the factors affecting growth in the industry and where growth was likely to take place. Twelve exhibitors had stands at the Congress. Attendees could choose from four post-event tours to Belguim/France (SADACEM/Compagnie Universelle d?Acetylene et d?Electro-Metallurgie), France (CUAEM), Finland (Outokumpu Oy) and Norway (Elkem Fiskaa plant).

Jan 1, 2004

By Silas C. Nichols

"Abstract Piling and deep foundations are a staple for transportation projects in the United States (US). Driven or bored piles have been used for everything from support of bridge foundations and retaining structures to support of culverts and embankments on soft ground. Deep foundations have been popular in the US transportation market to better handle large axial and lateral loads, extreme event loading, and to better control structure movement. However, there are challenges in the maintenance of design and construction codes in transportation for consistent and reliable structure foundation elements. A significant amount of effort continues in the US to maintain national codes and specifications at a level consistent with the state of practice, and identify and conduct research for providing safe and cost effective highway structures.IntroductionThe transportation sector in the United States has a hierarchy of design and construction codes that are used for the specification of piling and deep foundations. Any highway or bridge project on the National Highway System (NHS) must be designed and constructed in accordance with a national set of standards approved by the State Highway Departments, and that are acceptable to the Federal Highway Administration (FHWA). However, in any jurisdiction, exceptions are permitted with approval. Therefore, design may be governed by the national standard specification, a state standard specification and design manuals, special provisions, or guideline specifications. Any of these standards, or a combination, may be used depending on the needs of the owner agency.The FHWA and the American Association of Highway and Transportation Officials (AASHTO) have worked together in the development and maintenance of geotechnical design and construction guidance and codes that support the surface transportation community. General geotechnical engineering practice in the United States lacks a singular, national design and construction code that addresses all aspects of geotechnical engineering. As a result, the AASHTO specifications provide the most complete geotechnical specifications focusing on structure foundations, retaining walls, and buried structures for surface transportation applications. This includes piling and deep foundation types commonly used for support of bridges and transportation structures.The FHWA National Geotechnical Team has published several technical guidance documents that include guideline specifications for the design and construction of driven and bored deep foundations. Reference documents published by FHWA summarize the state of practice and provide recommended design and construction guidance. These reference documents have long served as a basis for provisions included in the AASHTO specifications. Maintenance of the design code and specification, and related guidance documents for consistent use on US transportation projects requires a collaborative effort between industry, FHWA, and the member state highway departments that make up AASHTO."

Jan 1, 2014

Research 82 highlights significant studies conducted during the past fiscal year at Bureau facilities and offices. Readers who want more information about the projects and studies summarized here can contact the researchers whose names and locations appear with each summary. General information on Bureau of Mines programs is available from the Office of Technical Information, 2401 E Street, NW., Washington, D.C. 20241. A listing of principal officials, a location map of field facilities, and a selected bibliography of publications and patents issued on Bureau developments during the past 3 years are provided.

Jan 1, 1982

The Calypso geothermal field, mapped by the R V Sonne (cruise SO-135) in 1998, includes four main sites, the Northern Vent Area (centred on 37¦ 36.7'S, 177¦ 06.2'E, area 1.5 km2), Central Vent Area (37¦ 39.4'S, 177¦ 05.2'E, 1 km2), Southern Vent Area (37¦ 41.7'S, 177¦ 06.0'E, 1 km2) and Mercury Vent Area (37¦ 41.3'S, 177¦ 07.3 'E, 0.5 km2). Hydrothermal activity at the vent sites is controlled by minor, sub-parallel NE-trending normal faults. Gas bubble trails (C02) and shimmering hot water vent from fractures and joints between large blocks of silicified volcaniclastics and in depressions in the sediments at the base of these outcrops. Measured maximum vent temperatures are between 180¦C and 201¦C. Venting fluids are at, or just below, boiling for water depths of 200 m. Rock samples recovered by dredge from the sites include massive anhydrite, clay-altered pumiceous ash, silicified volcaniclastic sediments and volcaniclastic breccias cemented by sulphur. Clay-altered samples, dominated by randomly interstratified illite-smectite and accessory chlorite, indicate formation environments of 70¦C to 90 ¦C. Native sulphur is abundant throughout the samples. Fine-grained (<1 mm) disseminated pyrite and vein pyrite occurs in the clay-altered pumiceous volcaniclastics and argillites. In the Southern and Mercury Vent Areas, fine-grained orpiment, realgar and cinnabar have deposited in the sandy matrix of volcaniclastic breccias. Amongst the cinnabar, small (<2 mm) beads of native Hg formed on the surface of several rocks following their recovery. These samples also contained abundant light hydrocarbons, which coat the rocks with an oily sheen.

Jan 1, 1999

By Ken Goering, Steve Kral, William Gleason

"Once every four years, the global mining industry gathers in Las Vegas, NV for MINExpo International. According to the show’s organizer, The National Mining Association (NMA), about 44,000 people attended the three-day show from Sept. 26-29. It was a show that featured the latest and greatest in equipment and technology. It also served as the backdrop for a snapshot of the state of the industry and while the picture of a global industry is never completely clear at any one time, one thing that is evident is technology has become a major force in the way mining is done.Had it not been for the awe-inspiring “iron” that was on the show floor in the form of haul trucks and shovels weighing hundreds of tons, one could be forgiven for thinking that they were at the Consumer Electronics Show. From training simulators designed to give a realistic experience of operating mining equipment to virtual reality technology that can take the user into the depths of an underground mine or the middle of a mapped ore deposit, an overriding theme of MINExpo 2016 was that the mining industry is connected like never before.In the north hall of the Las Vegas Convention Center was the GE Mining booth that was designed to showcase its efforts to help create a mine that will be connected from the front office to the face of the underground wall or bottom of the openpit. GE Mining called its booth a digital mine, and it included a suite of technologies that can improve performance, reliability, safety and operations. GE Mining said it views each mine as a mini-city, requiring power, water and transportation. Intelligent, real-time monitoring across the mine allows operators to make data-driven decisions that improve equipment reliability and optimize mine operations for substantial savings. And GE Mining was just one of many exhibitors showing off software that allows various types of equipment to communicate. Its booth sat in the shadow of the Komatsu booth with its new 360-t (400-st) 980E-4 haul truck that included GE’s 360-t (400-st) electric wheel motor. This is just one example of how technology is connecting machines, operations and people around the world and how mining is moving forward."

Dec 1, 2016

By O. Llewellyn Jack

From September 1978 to December 1983, ESD Corporation (formerly a Division of FMC Corporation) undertook the development and testing of a bidirectional auger under contract with the U.S. Department of Energy. Underground testing began in August 1981 at Peabody Coal Company's Marissa Mine near Marissa, Illinois. The auger was developed to increase mine production and coal recovery without increasing land subsidence. It bored 4-foot-diameter by 10-foot-deep holes into pillars on 7-foot centers (each hole recovering 5 tons). All operating during this test was performed by maintenance personnel with the goal of finding ways to increase the machine potential. The maximum excavation rate achieved was 1.4 tons per minute. It was concluded that the concept of drilling short holes to extract coal from underground pillars without surface subsidence was practicable with a wheel mounted auger, but that more power was desirable for this mine, and that the hydraulically driven augering system that provided experimental versatility was not sufficiently reliable for production use.

Jan 1, 1983

By J. R. Evans

Mining claims must have a discovery of a valuable mineral deposit to be valid. When required, a Federal government mineral examiner makes a determination of validity and recommendations thereof to authorized management officials. The examiner should show whether or not an existing mining operation, or a proposed operation have economic viability. This is accomplished through an analysis of legal entities, land status and use, geologic and mineralogic relationships, and mining, milling and processing techniques considered in an appropriate economic evaluation framework. A framework involves market and market entry studies, reserve analyses, all costs analysis, royalty buyouts, tax structure, discount rate of return, and escalation and risk factors. An income approach to value is then used by means of a simple or complex discounted cash flow (DCF) analysis to certify validity. Whether one claim is owned by a single miner, or hundreds of claims are owned by a large corporation, thorough, fair, consistent, and appropriate economic concepts should be applied by the mineral examiner.

Jan 1, 1993

By P Gunn, M Watts

The general goal of passive acid mine drainage (AMD) treatment is to reduce levels of acidity and metals to acceptable levels. Most treatment systems use either an oxidising or a reducing strategy. In oxidising systems, alkalinity is added along with dissolved oxygen; in reducing systems, dissolved oxygen is removed (if present) and then alkalinity is added. It is recommended that small-scale field trials be conducted as part of the methodology of selecting the best remediation strategy at AMD sites. Following successful field trials at the Sullivan Mine AMD, the Pike River Coal Company (PRCC) has shown foresight by using the same system to treat AMD generated as a result of taking a bulk sample of coal at the Pike River coal field. The system reduced acidity by 100 per cent, iron by 99 per cent, aluminium by 96 per cent, nickel by 95 per cent, manganese by 51 per cent and zinc by 99 per cent. The success of this field trial suggests that a system using a reducing strategy may be appropriate for the Pike River Adit AMD site.

Jan 1, 2005

By Junhwan Lee

Pipe piles can be either closed- or open-ended piles. Pile load capacity for a closed-ended pile consists of the shaft and base resistances, while, for an open-ended pile, it consists of shaft, soil plug, and annulus resistances. In order to investigate the pile load capacity of both closed- and open-ended piles, two field pile load tests were performed. For the open-ended pile, the fully instrumented double-walled system was used to separately measure all the components of the pile load capacity. The soils at the test site were predominantly granular soils with relative densities varying from loose to dense with increasing depth. The incremental filling ratio (IFR), which affects significantly the load capacity of open-ended piles, was also measured during pile driving. The test results indicated that the total load capacity of the closed-ended pile was higher that that of the open-ended pile, mostly due to the difference in shaft capacity. The shaft and base load capacities of the open-ended pile were 44% and 20% lower than the corresponding values for the closed-ended pile.

Jan 1, 2003

Mine Terex articulated dump trucks are working on a large restoration project of an abandoned open cast coal site in Blacklaw, central Scotland. The project is part of the construction of a 42-turbine wind farm complex. During the scheduled 18-month duration of the project, three 28-t(31-st) Generation 7 TA30 dump trucks and the six 36.5-t (40-st) TA40articulated trucks are estimated to move about 1Mm3 (1.3 million cu yd)of material. The trucks are working12-hour shifts, 5.5days a week.

Jan 1, 2005

When science and the human spirit come together amazing things can happen. This was perhaps never more evident than through the events that unfolded during August and October in a remote desert in northern Chile. On Aug. 5, the main shaft of the San José copper and gold mine near Copiapó in Chile?s Atacama Region collapsed, leaving 33 miners trapped more than 624 m (2,000 ft) beneath the earth?s surface.

Jan 1, 2010

By Mary L. Pearson

Ibis report summarizes the results of the contract. Included are summaries of existing legislation pertaining to outcrop barriers and a state-of-the-art survey of outcrop barrier designs and related, mine closure techniques. Six sites were inspected in the field and are presented as case histories The data analysis presented includes a computer modeled seepage analysis, an overburden blew-out analysis, and a wedge stability analysis. The results tit these analyses are interpreted to form recommendations for coal outcrop barriers which will minimize seepage and the potential for failure. Supplementary support and reinforcement alternatives are also discussed.

Jan 1, 1981

"INTRODUCTION Industrial utilization of the present submarginal domestic manganese resources of the United States is wholely dependent at this time on the electrolytic manganese process established as the result of 4 years of continuous operation of the Bureau of Mines pilot plant at Boulder City and 7 years' operations of the Electro Manganese Corporation commercial plant at Knoxville, Tenn.Three Kids ore provided the feed for the Boulder City pilot plant during 3 years of operation. Hence, the electrowinning characteristics of the ore have been thoroughly established, making possible accurate estimates for commercial operations.Before the Defense Plant Corporation constructed the leaching plant, the Bureau of Mines conducted an exploration project to determine the extent and grade of the ore reserves. Additional exploration, development, and mining by the Manganese Ore Cc, have accurately determined the tonnage and grade of ore. A large tonnage of stock piled ore is now available for immediate processing, and a considerable tonnage of openpit ore has been stripped of overburden preparatory to mining. Numerous facilities, such as power, water, and housing, needed for an electrolytic manganese plant are already available.All of these factors, as well as plans for installation of scale electrolytic manganese plant facilities, are presented in detail in the chapter entitled, ""Mining and. Electrolytic Reduction of use from Three Kids Manganese Mine."" The Manganese Ore Co. kindly provided information on the present ore reserves and state of development of the mine."

Jun 1, 1945

By Robert S. Schechter

A minitest, consisting of an injection/production well and at least two observation wells designed to detect the arrival of injected fluid leached minerals, and nonideal flow, is considered in this report. The test goals are to determine the susceptibility of the host formation to uranium leaching, kinetic parameters to scale the process, and to facilitate site restoration. This report considers permeability and mineral heterogeneities and other oxidant-competing minerals. To circumvent these nonidealities, which obscure the results, methods of interpretation have been proposed and tested by a computer simulator. In complex cases, clear-cut methods of interpretation were not found; but in every case the design of a test most susceptible to interpretation has been considered. The minitest is operationally simple and can be completed in a short time. With the correct design and interpretation it can return information to evaluate economics, ensure satisfactory leachate performance, scale to larger operations, and to identify restoration problems.

Jan 1, 1983

Watershed Jll in Jefferson County, Ohio we instrumented in 1977 as one of three watersheds established for the purpose of investigating surface mining and reclamation effects upon local hydrology, sediment discharge, and sediment and water quality. Each watershed was less than 50-acres in size, and was in a different geologic setting within southeastern Ohio. Surface runoff and ground¬water levels were monitored. Samples were taken for sediment determination and chemical analysis prior to mining. Monitoring and sampling continued through the period of watershed disturbance caused by mining and reclamation activities, which began in May 1980 at Watershed Jll. A psuedo-postreclamation period followed the initial cessation of man-machine activity on the watershed. A second reclamation effort occurred in the fall of 1981 and was to be followed by a third in 1982 after observations ceased. A true final postreclamation period was not monitored at this site, because the erosion control practice (terrace diversions) failed after each reclamation. Watershed Jll was a small pasture and wooded watershed with sandstone and shale above the mined coal seam prior to mining. A clay layer under the coal supported a perched saturated zone, termed the top aquifer for convenience. A lower underclay supported a second saturated zone called the middle aquifer. A lower perched aquifer had been dewatered by previous deep mining. After about three years of premine data and about two and one-half years of mining reclamation and psuedo-postreclamation data, the following general observations may be made: 1. The mining-reclamation phase was very short, and the postmining period was characterized by erosion failures and remedial disturbances that kept the watershed condition and size in a state of change. It was impossible to collect sufficient data to confidently characterize the hydrologic-sediment-chemical aspects of the mining period or of a postreclamation period and, most importantly, of the future watershed after its various properties and characteristics have ceased adjusting to its severe disturbance and reconstitution. 2. A seeding of wheat followed by grasses and legumes was not a particularly successful reclamation practice in terms of stabilizing the new soil. Numerous rills and small gullies developed in spite of installed diversions. 3. Storm runoff rates and yields at the watershed outlet increased from the premine, (phase 1) to the mining-reclamation (Phase 2) periods, and remained at or near the Phase 2 level through the postreclamation (Phase 3a) period. 4. The top aquifer changed in physical and chemical character as a result of mining and was becoming reestablished as the project drew to a close; but it is impossible to predict its final configuration or character. 5. Dewatering of the top aquifer resulted in a complete cessation of baseflow because the middle aquifer water table lay below the elevation of the watershed outlet. 6. The top and middle aquifers were merged in one area of the watershed where the upper coal underclay was disturbed. 7. Failure of the diversion terraces and their outlet obscured the effects of the reclamation practice upon sediment concentration and yields. There was little difference in sediment concentrations between Phases 2 and 3a. 8. Drinking water standards were met by surface waters throughout the period of observation except for two samples that exceeded the nitrate-N allowable level of 10 mg/l. 9. In all Phase 3 surface-water samples, iron concentrations were within the limits established by OSM, and manganese concentrations exceeded the regulation level only once. pH fell below the lower regulation level of 6.0 between 10% and 20% of the time. 10. The chemical quality of sediments was generally about the same after reclamation as before mining, with the exception of organic carbon, which decreased.

Jan 1, 1983