Abstract: The generation and release of acidic drainage containing high concentrations of dissolved metals from decommissioned mine wastes is an environmental problem of international scale. A potential solution to many acid drainage problem is the installation of permeable reactive walls into aquifers affected by drainage water derived from mine waste materials. A permeable reactive wall installed into an aquifer impacted by low-quality mine drainage waters was installed in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The reactive mixture, containing organic matter, was designed to promote bacterially mediated sulfate reduction and subsequent metal sulfide precipitation. The reactive wall is installed to an average depth of 12 feet (3.6 m) and is 49 feet (15 m) long perpendicular to ground water flow. The wall thickness (flow path length) is 13 feet (4 m). Initial results, collected nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. Comparing water entering the wall to treated water existing the wall, sulfate concentrations decrease from 2400 to 4600 mg/L to 200 to 3600 mg/L; Fe concentration decrease from 250 to 1300 mg/L to 1.0 to 40 mg/L, pH increases from 5.8 to 7.0; and alkalinity (as CaCO<inf>3</inf>) increases from 0 to 50 mg/L to 600 to 2000 mg/L. The reactive wall has effectively removed the capacity of the ground water to generate acidity on discharge to the surface. Calculations based on comparison to previously run laboratory column experiments indicate that the reactive wall has potential to remain effective for at least 15 years.

Abstract: Much work has been carried out in recent decades concerning minewater treatment, both in the UK and worldwide. Many different bodies and organizations are involved in developing minewater treatment processes and schemes. Minewater Treatment addresses the need for a single source of state-of-the-art information that draws all the latest research material together. Key features of the book include: a full literature review of minewater treatment throughout the world; an overview of relevant legislation and policy in a global context; a review of currently available methods for treating minewater worldwide; a site specific inventory of minewater treatment schemes within the UK, including compilation of available monitoring data and assessment of performance; a review of emerging and innovative minewater treatment technologies and consideration of related academic research within the UK; a comprehensive list of active and innovative minewater treatment technologies that are not currently compiled in a book or other review publication; a detailed summary and recommendations section assessing the applicability, efficiency and cost-effectiveness of minewater treatment schemes. Relevant scientific subject matter is presented in a concise, easily accessible manner to assist with the objective assessment of the progress made to date. Heavily illustrated with many colour photographs, the book allows best use to be made of the collective experience of minewater treatment practitioners throughout the UK, whilst at the same time placing the UK experience within a global context. An invaluable reference work for mining companies, consultants, planning officers, environmental research scientists, environmental agencies, water utilities and regulatory bodies, Minewater Treatment is a definitive source of information on minewater treatment technologies and will help facilitate the selection of the most appropriate technique required to tackle particular minewater discharge problems. Contents 1. The mine water problem 2. Treatment options 3. Existing sites in the UK: Case studies 4. Existing sites in the UK: Site summaries 5. Summary & conclusions