Towards an ecologically and economically reasonable management of mineral resources

EXCAVATIONS:GROUNDWATER Construction of the Chungho line, part of Taipei's mass rapid rail transit system involves tunnelling and construction of four underground stations in difficult ground conditions and narrow and congested sites. This article describes the geology of the area which comprises predominantly layers of loose alluvial sediment overlying a variable rock zone, and design and construction of the stations and tunnels. Station diaphragm walls and ground treatment involving installation of grouted blankets, compaction grouting and horizontal dillling to stabilise ground are detailed. Earth pressure balance machines are being used to drive the eight separate tunnel sections. The waterproof segmental lining system is outlined. Eight cross passa .ges will connect the tubes. Machine launch considerations m these sections are described. (J.M.McLaughlin)

Groundwater problems and environmental effects 966344 The protection of groundwaters from the effects of waste disposal P. A. Hart & I. Davey, in: Engineering geology of waste disposal, ed S.P. Bentley, (Geological Society of London; Engineering Geology Special Publication, 11), 1996, pp 361366. Powers available to the N R A are summarized. Definitions of waste and groundwater are given. The scale of the problem is described by reference to the legacies of historical 'dilute and attenuate' landfills, mainly occupying disused surface mineral excavations. An explanation is given of an interpretation of the National Rivers Authority 'Policy and Practice for the Protection of Groundwater' in context of waste disposal. Reference is made to work regarding best practice for containment and management of leachates generated at landfills. Scenarios are described which are then used to assess the likely impact of the policy on the future of waste disposal. It is concluded that the NRA's policy provides a framework used to promote the protection of groundwater resources. (Authors) 966345 Investigation, hazard assessment and remediation of existing landfills A. H. Marsh & A. Garnham, in: Engineering geology of waste disposal, ed S.P. Bentley, (Geological Society of London; Engineering Geology Special Publication, 11), 1996, pp 3-7. Any attempts to engineer the containment of waste and control the spread of pollution from it were the exception not the rule until the Control of Pollution Act .(1974), which came into effect on 1st January 1976. This date, with a few enlightened older exceptions, represents the start of modern landfill science and engineering practice in Britain. The second notable event was the explosion of landfill gases in March 1986 which destroyed a house at Loscoe adjacent to a landfill in Derbyshire. This brought landfills very much to the attention of central government, local authority Environmental Heath Departments and planners. The third major event was the passing of the Environmental Protection Act (1990), EPA, which in general terms introduced the concept in law of 'the polluter must pay' principle, followed by the proposed 'Landfill Tax' introduced in the 1994 budget. (from Authors) 966346 Development of a lined landfill site adjacent to a major potable supply river J. P. Apted, M. Philpott & S. W. Gibbs, in: Engineering geology of waste disposal, ed S.P. Bentley, (Geological Society of London; Engineering Geology Special Publication, 11), 1996, pp 367-372. The site at Pen-Y-Bent is based on a deep clay pit in Ruabon Marl and is on a piece of land almost completely surrounded

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by a loop in the River Dee, a major source of potable water. The proposals for developing a landfill at the site required two stages of investigation with particular regard being given to permeabilities and groundwater flow. A strategy for landfilling was developed that took into account the need to protect the Dee with particular emphasis being given to leachate control. In addition, the requirements for landfill liners in terms of current guidance were also considered. (Authors) 966347 Engineering geological and legal aspects involving proposals for a large waste disposal facility The Netherlands P. M. Maurenbrecher, in: Engineering geology of waste disposal, ed S.P. Bentley, (Geological Society of London; Engineering Geology Special Publication, 11), 1996, pp 373377. In the densely populated area of the Netherlands proposals for a waste disposal tip can involve drawn-out legal proceedings before permission is granted. A case history is given in which the author acted as advisor for one of the objectors to the scheme and hence gives insight into shortcomings in the quite extensive environmental laws concerning, amongst other items, waste disposal facilities. (from Author)

966348 Landfills and associated leachate in the greater Durban area: two case histories F. G. Bell, A. J. Sillito & C. A. Jermy, in: Engineering geology of waste disposal, ed S.P. Bentley, (Geological Society of London; Engineering Geology Special Publication, 11), 1996, pp 15-35. Two waste disposal sites in the greater Durban area used for codisposal of solid and liquid wastes are considered. One site is still operational and the other has been closed for a number of years. An investigation of Site 1 revealed that much of the area is covered by Berea Red Sand. This means that is has a low permeability. The very high values, for example, of chemical oxygen demand are attributable to a large extent to the disposal of hop waste. Accordingly the leachate is conveyed from a sump at the toe of the landfill to a sewerage works. At site 2 very little has been done since its closure to ensure that leakage from the landfill does not pollute the surrounding ground or surface waters. An investigation was undertaken to determine the extent of the pollution and revealed that a plume extended some 300 m downstream of the leachate pond. Two main remedial measures were proposed. First, a subsoil drain should be constructed immediately downstream of the landfill site. Secondly, a cement-bentonite cut-off trench, founded in bedrock, should be constructed 3 m downstream of the subsoil drain. (from Authors) 966349 Okologische und okonomische Rahmenbedingungen der Kiesbewirtschaftung (Towards an ecologically and economically reasonable management of mineral resources) H. C. Binswanger & C. P. Siegenthaler, Eclogae Geologicae Helvetiae, 88(2), 1995, pp 421-434. The management of mineral resources especially gravel and rock material in Switzerland shows two challenging characteristics: on the one hand, these materials represent the almost only nonrenewable resources which can be fully supplied by domestic (Swiss) reserves. On the other hand, the extraction of these materials is strongly linked to the use of land and therefore confronted with increasing conflicts in the allocation of landuse. This trend rises the question if the state authorities should take measures to control the extraction and marketing of gravel and rock material and which instruments could be used to install an ecologically desirable and economically allocation. The authors take a more functionoriented perspective and ask how the supply of these functions could be organized by materials or by techniques. An ecologically and economically resonable management of

EXCAVATIONS:GROUNDWATER al resources must aim at an absolute reduction in 6ty of material, a far-reaching use of recycling oppores and above that at an environmentally careful extracof the remaining resources needed. (from English rarY) 50

tion- the legacy

of the Welsh metal mines lsley, Mine & Quarry, 24(7), 1995, pp 9-10. egacy of the decline in metal mining in Wales is seen in unsightly spoil mounds, dangerous open shafts and rumbling remains of buildings. Many of the former ngs are sources of both airborne and waterborne tion affecting their immediate surroundings and more te localities. As such, the metal mining legacy is often d negatively. However, local authorities and funding s such as the Welsh Develoument Aeencv (WDA) have taking a fresh look into the signi&an&‘of the sites, uily from a safety and pollution prevention viewpoint, also from an industrial, archeological, geological and @al point of view. (from Author) 51 r movement in fissures in soil body disturbed by ~g(in Cbinese) 5 Yonghong, Wang Yuping, Yin Zengde L Sun ning, Journal - China Coal Society, 20(6), 1995, pp 71. osmotic spatial structure of fissures of soil body bed by mining is a special deformation medium. The and property of the fissure wall are important aspects. I flow in the fissures, including directional and peneg flow, as well as interaction between soil and water are rsed. The flow rate of water is controlled by the critical velocity of water level and the effective duration. The hydraulic parameter which affects the flow is the width : fissures. (English summary) 52 ods for the control

and treatment

of acid mine

?eRobinson & G. A. Robb, Coal International, 243(4), pp 152-156. .rainage of waters from abandoned coal and metal mines ten acidic with an elevated heavy metal content. t&ion between this acid mine drainage and the environcan cause gross pollution. Whilst temporary engineered fiation can lessen the impact, complete amelioration is possible using active and/or passive treatment systems. e technologies are costly as they often include the olled addition of chemicals which can produce a minated efluent that requires additional treatment. cience. of wetland treatment processes is still not fully ,stood and as a consequence the full potential of the ology has yet to be realised. There is evidence, however, the use of passive treatment is a realistic and cost ive method for the remediation of acid mine drainage. Authors) 53 tation of phosphate pebble as a precipitant for acid drainage treatment Chan Choi & T. R. West, Environmental & Engineering :ience, l(2), 1995, __ pp 163-171. ratory testing was performed to evaluate the effective)f uhosnhate nebbles from Florida in the treatment of n&e d&inage*under aerobic conditions. Using different rates, results show that phosphate pebbles effectively red ferric iron up to 1200 mg/l, aluminum up to 800 mg/l ulfate up to 8600 mg/l in three weeks. This method can plied to reduce acid mine drainage from old coal refuse even those containing high concentration of ferric iron Juminum ions. (from Authors)

966354 Evaluation of a composite soil cover to control acid waste rock pile drainage A. V. Bell, M. D. Riley BE E. K. Yanful, CZM Bulletin, 88(995), 1995, pp 41-46. At the Heath Steele Mines 10 000 mt of waste rock was placed on a prepared sand base with an underlying impermeable membrane. The waste rock pile was heavily instrumented for measuring oxygen concentrations and temperatures. A wmposite soil cover was placed over the pile, creating a totally enclosed system two years later. Moisture content and oxygen probes were installed within the composite soil cover to monitor changes within the soils over time, while two largesize lysimeters were installed below the cover to monitor the hydraulic conductivity of the cover. The monitoring shows very clearly that the piacement of the composite soil cover has had a major impact on the generation of AMD. Major reductions in temperature and oxygen concentrations within the waste rock pile indicate that the wver has significantly inhibited the oxidation reaction that generates the AMD. Performance data have shown that the wver has maintained its integrity under the climatic conditions of the area. (from Authors) 966355 Submarine tailings disposal (STD) for mines: an introduction D. V. Ellis, G. W. Poling & R. L. Baer, Marine Georeswrces & Geotechnology, 13(1-2). 1995, pp 3-18. The basic submarine tailings disposal (STD) design consists of a tailings line to a deaeration/mixing chamber, with a seawater intake line, and discharge to location and depth allowing gravity flow of a coherent density current to final sedimentation area. Such STD systems can place mine tailings at locations and depths constraining environmental impact to: 1) restricted areas of seabed, and 2) deep water turbidity. The US Bureau of Mines in the past 4 years has reviewed a number of aspects of STD. The reports include an estimate of the extent that STD could be used in the US provided satisfactory environmental screening criteria can be developed. The reports also include a bibliography, a review of potential biological consequences of STD, two volumes of case studies, and a review of regulatory aspects for a particular case. (from Authors) 966356 Quartz Hill, Alaska: a case history of engineering aad environmental requirements for STD in tbe USA C. A. Hesse & D. V. Ellis, Marine Georesources & Geotechnology, 13(1-2), 1995, pp 135-182. The Quartz Hill molybdenum prospect, with an estimated tailings disposal rate of up to 80 000 tons per day, was developed through preliminary engineering design, environmental impact assessments, and permit applications during the 1970s and 1980s. The intent was to meet the stringent environmental requirements of several federal and state regulatory agencies. The case history of mine development, extending over two decades, provides a unique set of details usable by future large-male coastal and island mine prospects in the US and elsewhere. Two fjords provided options for submarine tailings disposal (STD) with conventional deaeration and seawater mix chamber. An outfall was designed, and would be located, to produce a density current descending to fjord bottom. Innovative modeling of near-field and far-field tailings dispersal, and resuspension potential, was developed and applied. (from Authors) 966357 Tailings disposal at a marine placer mining operation by WestCold, Alaska R. H. T. Garnett & D. V. Ellis, Marine Georesources & Geotechnology, 13(1-2), 1995, pp 41-57. From 1985 to 1990 WestGold managed a marine placer mining operation with substantial documentation concerning its submarine tailings disposal (STD) system. For 5 years the