Mine Water Hydrogeology and Geochemistry

Y.T. John Kwong

CANMET Mining and Mineral Sciences Laboratories, 555 Booth Street Ottawa, Ontario,K1A 0G1

jkwong@NRCan.gc.ca



Edited by P.L. Younger and N.S. Robins Geological Society, London, Special Publication 198, Geological Society Publishing House, Unit 7 Brassmill Enterprise Centre, Brassmill Lane, Bath, Somerset BA1 3JN, UK ISBN 1-86239-113-0. October 2002 Hardback. 408 pages List price £85.00 / US$142.00 Also available from AAPG Bookstore P.O. Box 979, Tulsa OK 74101-0979

1 This book comprises 26 papers derived from a meeting of the Hydrogeological Group of the Geological Society of London in February 2001 and some additional contributions. Neither the theme of the meeting nor the exact number of additional papers is revealed. The topics range from in-depth reviews and detailed case studies on the hydrogeological and/or geochemical aspects of both operating and closed metal and non-metal mines to cursory accounts of modeling exercises and environmental impact assessments. As such, the papers vary in quality and the collection as a whole, in the absence ofa preface providing synoptic comments on the individual papers, appears to be unorganized. With a few exceptions, the more than 200 illustrations are generally easy to understand and the papers relatively free of typographic errors. However, North American readers may have to contend with a few unfamiliar mineral names (some of which are obsolete) without a given chemical composition and the rather odd usage of some familiar terms (e.g., petrological instead of petrographic analysis; mineralogy in place of minerals, tailings dam meaning tailings impoundment, etc.).

2 Upon closer perusal, it appears that the editors have tried to strike a balance among papers with a focus on coal mines (9 papers), metal mines (9 papers) and miscellaneous topics of general interest (8 papers, including two dealing with both coal and metal mines). Particularly outstanding in the first group of coal papers are an overview on the effects of longwall mining on aquifers (Booth), and a case study on the assessment, prediction and management of long-term, post-closure water quality at a South African coal mine (Hattingh et al.). In lucid terms, Booth first elaborates the mechanisms and impacts of the hydrogeological response to longwall mining. With reference to long-term investigations at two sites in Illinois, USA, he then illustrates the application of the derived general conceptual model and demonstrates that different responses could result from minor variations in geological setting within the same coalfield. From another continent, Hattingh et al. documents an exemplary multidisciplinary effort that integrates situation analysis, hydrology, hydrogeology, mineralogy, predictive geochemical modeling and systems environmental management, to address residual impacts after mine closure at the Hlobane Colliery. The remaining seven papers are derived from case studies at UK coalfields, with three focused on hydrogeological aspects (such as mine water recovery rate and impacts), two on hydrochemical issues (mine water fingerprinting and iron release modeling) and two attempting to integrate both aspects. In general, an empirical approach is emphasized in these case studies with the consequence that the conclusions drawn may not necessarily apply to coalfields elsewhere with different geological settings.

3 The second group of papers on metal mines are based on case studiesof mostly abandoned or closing minesin Europe (4 in UK and 1 in France), Africa (2) and South America (2). Among these, three hydrogeological modeling papers address the issues of water rebound in an underground tin mine, depressurization of a pit wall in an open-pit copper mine and structural control of contaminant migration in a tailings impoundment of a lead-zinc mine. Integrating hydrogeological and hydrochemical observations at large-scale gold mines and a silver-tin mine, two other papers emphasize the importance of collecting relevant data for environmental-impact and risk assessments. The remaining four papers focus mainly on water-quality issues, with topics ranging from geological materials as a source or sink of metal contaminants to arsenic removal by oxidizing bacteria. With the exception of the modeling papers, most articles are well referenced with conclusions clearly supported by the data furnished.

4 The last group of papers of miscellaneous interest is apparently intended to expand the scope of the conference volume and includes several interesting, albeit somewhat controversial, articles. As an opening overview paper, Younger and Robins (the editors) discuss challenges in characterizing and predicting the hydrogeology and geochemistry of mined ground, apparently perceived as the thread connecting many of the papers scattered in the book. The authors conclude with the concept of "defensive mine planning" and a suggested list of relevant measures, the majority of which have already been incorporated in the mandatory environmental impact assessment of any significant proposed mining operations in North America. There are two additional overview papers in the group. Augmented with a case study, Wolkersdorfer lucidly describes the applications and outlook of tracer tests in mines. Bowell presents a well-referenced and comprehensive review on the hydrogeochemical dynamics of mine pit lakes, despite some complicated diagrams that fail to clearly demonstrate the detailed processes involved or contain apparently unbalanced chemical equations. Two potentially contentious papers are also found. One is on the prediction of mineral weathering rates at field-scale based on simple scaling of physical parameters without considering detailed water-rock interactions. The other is on modeling sulfide oxidation in an unsaturated soil with the conclusion that pyrite oxidation by ferric ion is not faster than that by oxygen. The remaining three papers include a case study on the hydrogeological and geochemical interactions of adjoining mercury and coal spoil heaps in Spain,a brief description of alkaline mine drainage from metal sulfide and coal mines in Svalbard and Siberia, and an assessment of liabilities at a uranium mine the Slovak Republic. Incorporating few detailed hydrogeological and hydrochemicaldata, the last paper hardly fits the theme of the book.

5 In conclusion, compared to many conference volumes, this Geological Society Special Publication is a good-quality product. It contains many excellent overview papers and case studies. Readers interested in the hydrogeology of coal mines, in particular, may find many papers highly informative. Readers with a special interest in detailed mine water geochemistry, on the other hand, may find many of the papers lack the more vigorous data analyses commonly emphasized in more specialized publications. Moreover, the wide variety of topics covered in the absence of a synopsis chapter or preface makes navigating through the book somewhat difficult. At a price of US$142.00, the reviewer does not think that the book belongs to the must-have category.