• How are the effects of mining on water quality monitored?

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    Because of water quality concerns, surface and groundwater at mine sites is monitored before, during, and after the operation of the mine. The information collected by water monitoring programs is used to assess the effects of the mine on the surrounding environment and develop appropriate water management plans.

    Environmental assessment and baseline studies

    Because metal mines tend to be established in areas with naturally high concentrations of metals, one of the most important objectives of an environmental assessment and monitoring program is to establish an accurate water quality baseline for surface waters that will be receiving mine waste water or effluent. [1] In this way, the water quality after the mine has begun operations can be compared with the baseline in order to determine whether the mine is affecting water quality. [1, 2]

    Water monitoring programs

    Governments and other agencies such as the World Bank set standards for defined parameters for effluent, which are used as a basis for granting a mining license or loan. [3] The standards require mine owners to monitor and, if the water exceeds the allowed limits for effluent, to treat contaminated waste water before discharging it into receiving surface waters. [4]

    In Canada, metal mine effluent must be monitored and reported, and meet authorized limits for dissolved arsenic, copper, lead, nickel, zinc, cyanide, radium-226, total suspended solids, pH, and toxicity as set out by the federal Metal Mining Effluent Regulations (MMER) under the Fisheries Act. [5] In addition, most provinces with metal mines in their jurisdictions regulate the mines on a case-by-case basis, using the federal regulations as a guide for defining local requirements. [6, 7] Mining effluent is sampled at a point right before it is discharged into the environment, which is usually the tailings pond at most metal and mineral mines. [5]

    Environmental effects monitoring

    In Canada, environmental effects monitoring (EEM) is a requirement for metal mines regulated under the Metal Mining Effluent Regulations (MMER), and is used to assess how well the MMER-authorized limits are protecting the aquatic environment. [8] EEM includes taking samples of fish and other aquatic organisms in receiving waters downstream from mines and comparing them with samples taken from nearby waters unaffected by mining operations. [9] Environmental indicators such as the size and weight of the fish, and the number of different species present, are measured and compared using statistics in order to determine whether the mine discharge is having an effect on the health of the ecosystem. [8] Mercury in fish tissue is also measured and compared with the human health consumption guidelines in order to assess the effects of the mining effluent on people who may be using the fish as a food source. [8]

    Groundwater monitoring and management

    The seeping or leaching of mine drainage water from waste rock piles or unlined tailings dams into groundwater aquifers is a potential source of water pollution from mines. [2] Groundwater contamination is of particular concern where the groundwater feeds surface streams or lakes, or where the groundwater is being used as a source of drinking water. [2] Because of these concerns, groundwater contamination prevention is a component of modern mine design, and a network of groundwater monitoring wells are installed in order to assess whether the preventative measures are working and provide an early warning system for spills or leaks. [2, 10] Unlike surface water, groundwater cannot be easily intercepted, and current treatment involves pumping and treating the groundwater or containing it underground. [2]

    Water monitoring following the closure of a mine

    Historically, mines were often abandoned and left without proper cleanup. As a result, most regulators and financial institutions worldwide now require mining companies to develop mine closure plans and place multimillion dollar bonds to cover all the costs of mine remediation and reclamation. [2] Ongoing water monitoring and treatment is often a component of mine closure plans. [11]


    Case Study: Brenda Mines, Peachland, B.C.

    The Brenda Mines near Peachland in the Okanagan region of British Columbia produced copper and molybdenum from 1970 until 1990 when it was closed due to depleted ore reserves. [12] Approximately 200 million tonnes of ore were processed, and 278,000 tonnes of copper, 6,000 tonnes of molybdenum, and 125 tonnes of silver were recovered. [12] The property was acquired by Xstrata PLC in 2006 when it bought all the outstanding shares of the previous mine owner Falconbridge Limited, which had merged with Noranda Inc. in 2005. [13]

    Site reclamation activities began in 1988 and consisted of demolishing and removing buildings, stabilizing rock piles, and planting grass, trees, and other vegetation on the site. [13] While the mine was in production, it operated on a closed-loop system, and no effluent was discharged from the tailings pond. [12] Fresh water was piped in from the nearby Peachland Lake for drinking water and use in mineral processing. [12]

    By the time of the mine’s closure, water had begun to collect in the open pit. The water management strategy was re-evaluated through consultation with government representatives and local residents. [12] Molybdenum was identified as a contaminant of concern, and molybdenum treatment by precipitation with iron oxide was determined to be the preferred water management option. [12] In 1997, an amended Permit to Discharge was issued under the provisions of the BC Waste Management Act, and in 1998 a new water treatment facility with a capacity of 313 litres per second was commissioned by the then mine owners, Noranda Inc., and began operations. [12]

    All rain and snowmelt that comes into contact with exposed rock areas on the closed mine site, along with any seepage from the tailings dam, is collected and stored in the open pit and tailings pond. [14] The water is pumped to the treatment plant, which adds ferric sulphate to the water to lower the pH to 4.5, the point at which molybdenum reacts with the iron to make a sludge. [14] The water is filtered, and the sludge is pumped to a storage pond onsite. [12, 14] Lime is then added to raise the pH before the water is discharged to a nearby creek. [14]

    Xstrata PLC continues to fund the water treatment, and two full-time Xstrata PLC employees currently oversee the water treatment and monitoring operations at the site, which have been estimated to be required for the next 50 to 200 yearsi. [12, 15] The performance of the water treatment plant has been better than expected, and the water quality monitoring results are provided to community members online and in newsletters. [14]

    iFuture purchasers of the site would be responsible for the maintenance of the water treatment plant, and the land will eventually be returned to the Crown

    Show References


    1 Hutchison, I.P.G. and R.D. Ellison, Mine Waste Management, 1992, Chelsea, Michigan: Lewis Publishers, Inc.
    2 Lottermoser, B., Mine Wastes: Characterization, Treatment and Environmental Impacts, 2012, Springer: New York. p. 400.
    3 Younger, P.L., S.A. Banwart, and R.S. Hedin, Mine Water: Hydrology, Pollution, Remediation, 2002, Dordrecht, The Netherlands: Kluwer Academic Publishers.
    4 Rankin, W.J., Minerals, metals and sustainability : meeting future material needs, 2011, Collingwood, Vic.: CSIRO Pub.
    5 Canada, Environment Canada. Guidance Document for the Sampling and Analysis of Metal Mining Effluents 2/MM/F/B, 2001 [cited 2012 May 30]; Available from: http://www.ec.gc.ca/Publications/default.asp?lang=En&xml=30EE2CC9-5118-4D47-A14B-B109294FCABA.
    6 Canada, Environment Canada. Mining, 2012 [cited 2012 June 13]; Available from: http://www.ec.gc.ca/pollution/default.asp?lang=En&n=C6A98427-1.
    7 Canada, Environment Canada, Mine and Mill Wastewater Treatment 2/MM/3E 1987, Environment Canada p. 96.
    8 Canada, Environment Canada. About Environmental Effects Monitoring, 2011 [cited 2012 June 14]; Available from: http://www.ec.gc.ca/esee-eem/default.asp?lang=En&n=4CDB9968-1.
    9 Canada, Environment Canada. Metal Mining Environmental Effects Monitoring Review Team Report, 2007 [cited 2012 June 14]; Available from: http://www.ec.gc.ca/Publications/933E74AE-6C80-4A54-9CAB-62E5A7440114%5Cmm_review_report_full_e.pdf.
    10 International Council on Mining & Metals. Water Management in Mining: A Selection of Case Studies, 2012 [cited 2012 June 12]; Available from: http://www.icmm.com/www.icmm.com/water-case-studies.
    11 Wolkersdorfer, C., Chapter 11: Mine Water Treatment and Ground Water Protection in Water Management at Abandoned Flooded Underground Mines: Fundamentals, Tracer Tests, Modelling, Water Treatment, A. International Mine Water and I. ebrary, Editors. 2008, Springer: Berlin. p. 235-277.
    12 Patterson, M. Water Management and Molybdenum Treatment at the Closed Noranda Inc. -- Brenda Mines Site, Peachland, BC., British Columbia Mine Reclamation Symposium 2003, 2003 [cited 2012 June 22]; Available from: https://circle.ubc.ca/bitstream/id/22209/05%20Patterson.pdf.
    13 Xstrata Copper Canada. History, Brenda Mines, 2012 [cited 2012 June 22]; Available from: http://www.brendamines.ca/EN/History/Pages/History.aspx.
    14 Xstrata Copper Canada. Water Treatment Plant, Brenda Mines, 2012 [cited 2012 June 22]; Available from: http://www.brendamines.ca/EN/WaterManagement/Pages/WaterTreatmentPlant.aspx.
    15 Xstrata Copper Canada. Reclamation, Brenda Mines, 2012 [cited 2012 July 27]; Available from: http://www.brendamines.ca/EN/Reclamation/Pages/Reclemation.aspx.

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