A classification system for pressures related to hazardous water emissions from mine sites - comparison of pressures in ten EU Accession Countries

ERIK PUURA

Institute of Technology

University of Tartu

Vanemuise 21

50110 Tartu, ESTONIA

MARCO D’ALESSANDRO

Institute for Environment and Sustainability

Joint Research Centre of the European Commission

I-21020 Ispra (VA), ITALY

Abstract

A survey of information on the hazardous water emissions from mine sites in the Central and Eastern European EU Accession Countries, as well as the overview of already existing ranking systems and studies in Europe, demonstrated a need to establish a common and easily understandable new ranking system for environmental pressures, that could give information on the existing situation with respect to mine waters and be used for assessments and comparisons on multicountry level and catchment basis. The proposed system uses and combines two main parameters characteristic to the mine site or a set of small mines polluting a certain water course – the flow rate of the emissions and its qualitative character expressed by the maximum value, how many times any of the environmental standards (maximum permissable concentration) is exceeded. These two parameters can be combined into one – pressure factor (PF), defined as log(number of times standard exceeded) + log(emission flow rate, m3/day). The data are expressed on a special plot, the five categories A…E define the number of times of the standard exceedance (A – more than 1000 times; E – not exceeded), the classes are also dependent on the flow rate. The available information and estimated parameters for different mining sites in Central and Eastern Europe were compared on a single plot, showing the differences of MPC exceedance and flow rates between emissions generated by the larger and smaller scale mining activities of different commodities.

Introduction

Mine accidents in Aznacollar, Spain in 1998, where a damburst poisoned the environment of the Guadiamar river, and the Tisza pollution caused by a cyanide spill following a damburst of a tailings pond in Baia Mare, Romania in 2000 increased public awareness of the environmental and safety hazards of mining activities in Europe. In mid-2001, Joint Research Centre of European Comission started a project ‘Inventory, Regulations and Environmental Impact of Toxic Mining Wastes in Pre-Accession Countries’ (PECOMINES), one of the objectives of which was to collect and analyse information on hazardous mine sites and mine wastes in Central and Eastern European Candidate Countries.

A prerequisite for the comprehensive overview of the existing problems is a set of criteria, according to which the comparisons on multicountry level could be made. The assessment of waste generation showed, that in many Candidate Countries (Czech Republic, Estonia, Bulgaria, Romania, Poland, Slovakia), the waste produced during the extraction and processing of the mineral resources ranks first both in quantity and creating environmental problems. The number of sites depended on the detailness of the inventories carried out on the national level and the total number reaches many tens of thousands, for example the Slovakian inventory only included 17260 sites. However, there were no commonly accepted criteria, according to which the preliminary screening of the huge number of the sites could accomplished in order to distinguish and compare the set of most hazardous ones in one country with those in another.

When comparing the situation in different countries, a basic question came forward – using which criteria it could be feasible to convert intuitive understanding of the ‘worst cases’ in different countries having a different impact to environment by many orders of magnitude (eg gypsum mines in one and very large metal mines in another country) – into a comprehensive ranking system. This paper summarises the efforts of some previous mine sites inventories in Europe, analyses the results of the PECOMINES questionnaire answers and proposes a new methodology for comparative assessment and ranking of mine sites with respect to hazardous mine water emissions.

The proposed methodology is envisaged to contribute to one part of the overall risk assessment – characterisation of the pressures through continuous water emissions, and does not consider the other problems related to mine sites, such as slope stability and on-site soil contamination.

Materials and methods

A multisource approach was used to develop a comparative assessment methodology, including

-  a review of previous comparative studies and methodologies in Europe

-  analysis of the information gathered by questionnaire approach

-  hydrochemical analysis of the test sites.

In a number of recent multicountry reviews, the source characterization that should be the first step in the complete procedure of risk assessment (Figure 1) has been accomplished on the basis of the amounts of mined commodities and/or disposed waste. The problem is, that neither of those would give correct prediction of the water pollution related environmental impacts even in the right order of magnitude. A small mine of sulphides from a quartzite host rock producing pH 1-2 leachate and a large brown coal mine with limestone dominating in the overburden with pH 7-8 leachate could be just two examples, why the exercise fails.

A logical way forward that has been suggested and developed, is a geoenvironmental model of a mineral deposit that provides information about geochemistry and its variations of a particular deposit type, and geochemical variations associated with wastes and effluents (Plumlee and Nash 1995). When becoming a major tool for environmental assessment in a mine planning process, the uncertatinties related to effluent quality of a particular deposit type still remain, as the number of parameters that control effluent formation and transport is still very large. Therefore, for already existing sites, the association between the magnitude of the water pollution related environmental impacts and the deposit types is also not straightforward, keeping in mind that the problems are already there and the number of sites is estimated at many tens of thousands.

Approaching the risk assessment procedure from the other side – identifying all possible pathways and targets and assessing the existing and potential damage – requires development of a large number of different criteria together with their weighting factors. As this has been already done in many countries separately, any harmonization of these

Figure 1. Generalised scheme

of the steps of risk assessment

methodologies is a cumbersome task. The categories ‘high risk’ and ‘low risk’ in different countries fully depend on the character and magnitude of the existing problems, and are often related to the opinions of local experts.

The underlying assumption in the development of the screening methodology states, that qualitative and quantitative characterization (measurement data or estimation) of the hazardous water emissions makes it possible to relate pollution potential to the possible set of environmental impacts. The justification of this statement is based on the differences in these emissions – both in flow rates of the streams and concentrations of different contaminants – by many orders of magnitude. Thus, even a rough estimation including certain uncertainty factor becomes a useful information, making quantitative comparisons possible.

Review of previous efforts

The simplified scheme of the sources for hazardous water emissions from the mine sites is presented on Figure 2. As a whole, a mine site can be considered as more or less complicated pattern of one, some or all these areas. The scheme does not include some more rare cases, such as in-situ leaching facilities and ex-situ hydrometallurgical leaching plants.

The emissions leaving the site and entering the catchment are impacting surface water bodies, groundwater, soils and sediments, these systems becoming both targets but also pathways. The final targets could be roughly grouped into human health-material values and ecosystems-protected areas.

Referring to this schematic approach, it is possible to define the scope and describe the content of a number of the previous multicountry and country-level comparative assessment efforts, demonstrated in Table 1. The descriptions do not attempt to provide a comprehensive overview of all existing efforts, but to demonstrate, what are the different efforts based on and how different the approaches are. The information was mainly collected on inventories of closed and abandoned mine sites. The number of these sites is very large and the information usually limited.

Figure 2. Simplified scheme of the source-pathway-target approach in mine and quarry sites context.

Table 1. Examples of the previous and on-going efforts to tackle mine sites problems

Effort / Scope / Description / Results
Multicountry efforts
The Multi Country PHARE PROGRAMME – Remediation Concepts For The Uranium Mining Operations in CEEC (MCP)
(Tabakov 2002) / 124 uranium objects in 9 CEEC countries, incl mine sites (Albania, Bulgaria, Czech Republic, Estonia, Hungary, Poland, Romania, Slovakia, Slovenia) / Compilation of an inventory of the existing situation; implementation of pilot projects; supporting co-operation between the involved countries / An unique systematic approach for determination of individual or/and group objects; collecting, validation and assessment of information for liabilities and impact on environment; implementation of unique scale for ranking and prioritization of objects in all participating countries, using a specially designed system for ranking; determination and implementation of Pilot Projects
A preliminary risk inventory of toxic waste storage sites in EU countries launched by WWF after Aznacollar accident (Sol et al 1999) / metal mining areas and tailings lagoons in EU countries / confrontation of the mine site locations with protected wetlands (Ramsar convention sites), as particularly vulnerable to pollution from mining activities / recommendation was made to use country-by-country approach towards all data owners, including national authorities, counties, local authorities and NGOs. It was also recommended, that analysis of satellite remote sensing data could speed up this process considerably
Management of mining, quarrying and ore-processing waste in the European Union, the study made after Baia Mare accident for DG Environment by BRGM (BRGM 2001) / Quantitative estimation of the mining waste in EU countries / a questionnaire approach in combination with calculations based on World’s average production-waste materials ratios for different commodities / The rough estimation of mining waste in different EU countries, schemes of typical hydrogeological settings for waste management facilities.
The Regional Inventory of Potential Accidental Risk Spots in the Tisa Catchment Area by the International Commission for the Protection of the Danube River and Zinke Environment Consulting (ICPD, 2000) / Sites of highest accident risk in Tisa Catchment on the territories of Romania, Hungary, Ukraine and Slovakia / Based on the national information provided, 3 risk categories were established, the high risk category being defined as information based indication for direct or indirect high accident risk (existing leakage etc.). / Among the hot spots related to various industries, 19 mining spots were assessed as at high risk in Romania (16 tailing deposits/ponds, 3 mines), 1 in Slovakia and 1 complex of reservoirs with mine and industrial metal sludge in Hungary.
Single country efforts
BULGARIA – BGP, BGPE (Tabakov 2002) / concentrated towards the problems related to the uranium production / a detailed inventory with site specific approach, but without national standards and real experience in some cases. / identification of objects, collecting of past data for inventory of liabilities, field measurement and samplings (water, soil, rock), laboratory test of samples, risk assessment (site specific and ranking system), grouping of objects, development of complex programme for remediation
CZECH REPUBLIC Impact of Mining on the Environment (Reichmann 1992) / 1:500000 scale map of Czech Republic with explanatory text and legend / Using the geological map with deposit boundaries and mining areas as a basis, a methodology assessing the individual impacts of 13 categories was established / The impact of factors was expressed in 3 categories: high risk, low risk and no risk, based on expert estimations. Altogether, 169 sites and their different risks were presented on the map. The quantitative criteria for different risk categories were not established.
POLAND, Polish Geological Institute (Dr M. Gientka, personal communication) / Geo-environmental maps of the scale 1:50000, the basis is a landuse map. / The mines presented on the maps are assessed site-specifically into non-conflicting, conflicting and very conflicting categories with the surrounding environmental system, settlements, protected territories and objects, etc / The 1:50000 scale maps provide a basis for solving the problems on local scale, case-by-case
PORTUGAL
(Da Silva Daniel 2002). / Program covering all abandoned mines / The ranking of the mine sites regarding the safety and environmental problems, including different weighting factors for mine safety, waste data (volume, stability and chemistry), chemical impacts to soil and water, visual impacts and landscape, and human presence and activities in the vicinity. / The final results ranked the sites into:
Degree 4 – High hazards
Degree 3 - Medium hazards
Degree 2 – Low hazards
Degree 1 – Negligible hazards
SLOVAKIA (Janova and Vrana 2002) / All active and old mining sites / registration, inventory and evaluation of present (active) mining sites of raw materials - 266 localities,
complex inventory of old mining sites – 17260 localities,
inventory and evaluation of impacts of all mining sites on environment,
preparation of state monitoring of the most risky localities of mining sector,
proposal and realisation of remediation activities / localities were categorised into 3 categories with uniqe methodology using different weighting factors,
I category –remediation is required as very acute step
II category –transitional position, not so critical or requires supplementary investigation to clarify situation (with possibility to re-categorise the mining site);
III category –apparently low or minor impact on human health, environment and estates
Based on ranking system, the I. category (and another three localities of the II. category) were denoted as “hot spots” for which the monitoring system is being developed.
SWEDEN Swedish EPA report ‘Methods for Inventories of Contaminated Sites’
(Swedish Environmental Protection Agency 2002). / Is orientated to local and regional authorities to make accurate assessments of environmental quality on the basis of available data, thus providing a more solid foundation for environmental planning and the establishment of environmental objectives / A contaminated site is defined as a landfill site or area of soil, groundwater or sediment, which is contaminated by a point source in the extent that the concentrations significantly exceed local or regional background levels. The assessment of the sites is based on environmental quality criteria – hazard assessment based on hazardousness of the chemicals, contamination level comparing the current conditions with reference values, amount and volume of the contaminated material, potential for migration and consequences – human sensitivity and protection value. / Definition of the classes of current conditions – 10 times exceedence of guidance values for state describes the sites as very serious (uppermost class), and 25 times exceedence of reference values of impact define the sites as belonging into the class of very large effect of point sources (also uppermost class)
UNITED KINGDOM (Jarvis and Younger 2000). / national dataset of the damage caused by abandoned mine discharges / Method of UK National Rivers Authority (now the Environment Agency): the severity of environmental impacts is measured sequentially in six categories:
1.Area affected (by deposition of metal precipitates, assessed visually);
2.Length affected (m);
3.Substrate quality and salmonid reproduction;
4.Iron deposition (the intensity of discoloration, assessed visually);
5.Total iron concentration;
6.pH, dissolved oxygen concentration and aluminum concentration.
After this ranking, benthic macroinvertebrates are used to determine water classes. / Indicates that some 400 km of watercourse are currently degraded by abandoned coal mine discharges, with a further 200 km contaminated by abandoned metal mine discharges. Within these UK totals, well over 90% of the total polluted drainage turned out to be accounted for by discharges from polluted mine voids rather than from old mine waste depositories. The extrapolation in the lack of European data suggests that the total length of watercourses polluted by mine drainage in the present EU may well prove to exceed 5000 km, with Candidate Countries adding their contribution (Younger, 2002). .

The comparison of international and country specific efforts shows the basic difference in approaches.