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SEARCH266OGHLI G H T S VI SIHenna Punkkinen Lea Räsänen Ulla-Maija Mroueh Juhani Korkealaakso Samrit Luoma Tiina Kaipainen Soile Backnäs Kaisa Turunen Kimmo Hentinen Antti Pasanen Sari Kauppi Bertel Vehviläinen Kirsti KrogerusHINS SC IE N CE TREGuidelines for minewater managementISBN 978-951-38-8443-7 (URL: N-L 2242-1211ISSN 2242-122X NOLOGY This report is a part of the WaterSmart project, which aims toimprove the knowledge of the actual water quantities and of thewater balances in mining areas. The report describes theguidelines and related good practices for water management indifferent phases of mining therefore enabling selection of the mostappropriate calculation models and measurements as well ascontrol, reporting and decision-making practices.Guidelines for mine water managementMining influences the quality and quantity of water in the mine areaand in its surroundings and changes hydrological conditions.Although mining companies have long been conscious of theimportance of water management, they still face environmentalproblems. In fact, water management is at the moment the mostchallenging stress factor concerning environmental safety inFinnish mines.VTT TECHNOLOGY 266Guidelines for mine water managementEC

VTT TECHNOLOGY 266Guidelines for mine watermanagementHenna Punkkinen, Lea Räsänen, Ulla-Maija Mroueh &Juhani KorkealaaksoVTT Technical Research Centre of Finland LtdSamrit Luoma, Tiina Kaipainen, Soile Backnäs, KaisaTurunen, Kimmo Hentinen & Antti PasanenGeological Survey of Finland (GTK)Sari Kauppi, Bertel Vehviläinen & Kirsti KrogerusFinnish Environment Institute (SYKE)

ISBN 978-951-38-8443-7 (URL: http://www.vttresearch.com/impact/publications)VTT Technology 266ISSN-L 2242-1211ISSN 2242-122X opyright VTT 2016JULKAISIJA – UTGIVARE – PUBLISHERTeknologian tutkimuskeskus VTT OyPL 1000 (Tekniikantie 4 A, Espoo)02044 VTTPuh. 020 722 111, faksi 020 722 7001Teknologiska forskningscentralen VTT AbPB 1000 (Teknikvägen 4 A, Esbo)FI-02044 VTTTfn 358 20 722 111, telefax 358 20 722 7001VTT Technical Research Centre of Finland LtdP.O. Box 1000 (Tekniikantie 4 A, Espoo)FI-02044 VTT, FinlandTel. 358 20 722 111, fax 358 20 722 7001Cover image: GTK

Executive summaryMining influences the quality and quantity of water in the mine area and in its surroundings and changes hydrological and topographical conditions, sometimesdrastically. According to the Finnish mine stress test study by Välisalo et al.(2014), water management is at the moment the most challenging stress factor inFinnish mines. In Finland, especially the problems with water balance management and large water quantities have lately been one of the main reasons causingenvironmental problems. The situation is similar also elsewhere, as in most partsof the world mining companies are exposed to some kind of risk related to theavailability of water. Either there is a lack of water or the contrary, there is toomuch water. Both circumstances can cause significant effects on the mining operations and the environment. The lack of comprehensive and practical tools forefficient water management seems to be one of the main causes behind the problem, as can be seen from the following list which describes the current needs ofmine water management that were identified in this report:Competence development and practical introduction of water managementand modelling toolsImproved (online) monitoring tools for data collection and organized datatransferoBoth water quantity and quality are important for optimal collection,treatment and recycling of watersUser-friendly water balance management toolsoQuickly updatable, user-friendly interfacesTools which enable integrating the water balances of different operations toone “site-wide-water-balance” taking into account both mine area and surrounding environmentoHow to overcome compatibility challenges between the different approaches used in planning?Integration of water balance management to process control system of themine3

A proper water management system can be beneficial to the mine. If the planningof water balance management actions has already been started in the early phases of the mine life cycle, several advantages can be gained. The reduction of risksand environmental impacts (e.g. preparation for extreme situations and changes ofthe water balance) is the most important asset, but early phase planning and datacollection are also important when achieving cost and waste reductions as thisenables an early phase modelling of the different scenarios and maximizes opportunities (Griffiths et al. 2008). Cost savings can be created, e.g. as a result of theuse of optimum size storage capacity, diversion of different water types, and optimization of water-recycling activities. Good environmental performance also increases the social acceptance of the mine.Water management is a continuous process that needs to be developed andupdated throughout the whole mine life cycle, for example when changes in mining operations also affect the water balance. In the different phases of a mine’s lifecycle, the water management program will change. Even within a phase, as information and data are collected, knowledge increases and the need for revision andupdating arises. As every site is unique, proper water management requires anunderstanding of the site-specific factors, and should always be applied casespecifically. The use of a pro-active approach aiming to solve the causes behindproblems beforehand instead of addressing symptoms is another key principle thatshould be followed when aiming for an efficient water management solution.The mine water management system includes water balance modelling and water quality and quantity monitoring. The difference between water managementand water balance is important. According to Mueller (2015), water managementis a practical management structure with a strategy and goal that is often environmentally driven. Water balance is just one tool to achieve this goal (Mueller 2015).The design of the mine water management system should include forecasting andsufficient monitoring of hydrological conditions, adaptation to potential risk scenarios and collection of water quality data. The minimum requirements for monitoringand reporting are laid down in legislation and permits. Due to recent mine waterbalance management issues in Finland, the legislative requirements have becomestricter, thus generating differences in requirements between “old” and “new”mines. Water balance management is also linked to waste management, as tailings ponds form a huge resource of contaminated mine water.Nowadays it is still quite common that a spreadsheet-based deterministic approach (e.g. Microsoft Excel) is used for water balance modelling. With the help ofspecialized add-in tools (e.g. to assess uncertainties), a spreadsheet can even actas a dynamic modelling tool. Spreadsheets are useful for easy projections, andthey can be rapidly implemented and used to store, display, and check dynamicmodel inputs, or display and analyze dynamic modelling results. However, theyare not transparent, nor very well suited for complex modelling. Spreadsheetmodels may also be prone to errors. Thus, the shift from deterministic methodstowards more versatile dynamic models that can be coupled to hydrological, geochemical, reactive transport and to chemical equilibrium models is needed. Incertain countries, such as Canada, the USA and some European countries, a4

dynamic approach is already commonly used in mine water balance modelling.The most well-known dynamic water balance simulator in mine water management is GoldSim. In addition to GoldSim, the dynamic simulators MATLAB Simulink, STELLA and Vensim are described in more detail in Section 5.2.2.2. Inaddition, the Watershed simulation and forecasting system WSFS is presented inthis same context. The report also introduces the hydrogeological and groundwater flow models MODFLOW, MT3DMS, FEFLOW, MODFLOW SURFACT, HydroGeoSphere (HGS) and PHREEQC, as well as the equilibrium and chemical models HSC Sim, PHAST, PHREEQC, TOUGHREACT, HYDRUS 2D/3D, ChemSheetand OLI, in Sections 5.2.2.3 and 5.2.2.4.A mine water quality and quantity monitoring program should encompass all thedifferent types of waters in the mine area, namely process waters, natural waters(such as groundwaters and surface waters), as well as wastewaters and/or usedwaters (such as tailings and dams), and be dependent on the mine characteristics,surrounding grounds and waters, and other site specific factors. It is critical tomonitor at least the water quality of outflow and discharge at sites downstream,but it is also advisable to study the water quality in the background and inside themine site. Some common parameters monitored include temperature (T), pH,electrical conductivity (EC), redox potential (Eh), dissolved oxygen (DO), alkalinity,metals and metalloids, nitrogen and phosphorus compounds as well as otheranions such as sulphate and chloride. The water monitoring should include themeasurement of physico-chemical quality and water level, in parallel with localclimate measurements. Surface water monitoring should also include flow measurements which are needed for water balance calculations. It is advisable to storeall data from monitoring in a database with easy access. Having a dedicatedweather station on site, whenever possible, is recommendable to gather accurateinformation and thus increase the reliability of the water management tools. Regular monitoring of surface and groundwaters and water levels combined withweather data is valuable for forecasting hydrological conditions and preparation forunexpected situations.Monitoring can be performed online or offline. Nowadays, for example, the water flow, level, pH, T, EC, DO, turbidity, NO3-N, and NH4-N can be monitoredonline. The possibility to integrate the data from online monitoring to water balancemodelling would be ideal. Continuous monitoring of water flow and water level inbasins is recommended as good practice, however, regular visual inspections ofbasins are still important to confirm the operation of monitoring equipment and thewater level in basins. Also the monitoring program should progress and developover the mine life-cycle phases as more information on water sources, use, discharges, etc. is attained. The first water-monitoring step is taken when the environmental baseline study is performed before any alterations to the proposed minearea are made. Meteorological information on the prevailing conditions at theplanned mine site should be collected for several years before mining activitiesand the monitoring program should be developed on the basis of critical assessment of this survey.5

General guidance on how water management should be performed in the different phases of the mine life cycle is given in Section 6.4. Water managementactions in the different phases of the mine’s life cycle and the related permits aregathered in Table 5.Chapter 7 summarizes the aims of a comprehensive water management program and gives the key points for setting up such a program in Finland. The chapter provides a brief overview of the evolution of the water management program indifferent phases of the mine life cycle. The infrastructure, techniques and technology are available to make the state of mine-site waters known to both mine operators and supervising officials. Speculations are also made as to how the management, software and monitoring will develop in the next decades.6