Context

The Irish Environmental Protection Agency (EPA), in conjunction with the Geological Survey of Ireland and with the assistance of the Exploration and Mining Division of the Department of Communications, Energy and Natural Resources, has produced a report on historic mine sites in the Republic of Ireland (RoI).  The recent Volume I covers data and characterisations on the geology of the sites as well as the chemicals found at the sites in various media (land, water, air) and a classification scheme that begins to measure the extent of the risks associated with the mining sites.

The report applies to “historic mine sites,” defined as closed mine sites not currently regulated under any permit or legislation and which sites include some infrastructure associated with mining operations, such as shafts, pits, tailings, spoil piles and other processing facilities.  The report was triggered, in part, by Directive 2006/21/EC of the European Parliament and of the Council on the management of waste from extractive industries.  This Directive amended Directive 2004/35/EC.  Under the Directive, member states are required to produce an inventory of such sites by 1 May 2012, and the inventory must be compiled on a risk basis.

Another trigger for such an inventory, no doubt, was the wide-spread concern about the risks presented by lead exposure to people and cows near the Silvermines site in Co. Tipperary in 1999, other risks at the Tynagh mining site in  Co. Galway, and protests against uranium mining in Co. Donegal.  Citizen activism at these sites represented some of the earlier instances of the development of the environmental movement in the RoI.  See Liam Leonard, Green Nation, below.

What Was Done

The report includes an assessment of 27 mines or districts, and included within the 27 are a total of 82 individual sites.  Some of the individual sites were worked closely together or by the same operators and are therefore combined into districts, although each mine site was also evaluated separately.

The evaluations are based on available information and some limited sampling, and classified according to a scoring system.  The scoring system, called the Historic Mine Sites Scoring System (HMS-SS), was developed to prioritise the historic mine sites based on their impact on human and animal health and on the general environment. The system is based on the Abandoned and Inactive Mines Scoring System (AIMSS) which was developed to carry out a similar exercise in the US State of Montana.  The report makes it clear that the HMS-SS is not a detailed quantitative risk assessment, but rather is designed to rank sites using existing or easily obtained information on the basis of threats to human health, animal health and the environment.  See the description of “risk assessment” in the “iePEDIA” section of irish environment.

The scoring system is very technical and detailed, and an understanding of those details is not essential to appreciating the conditions that exist at the sites and what risks, actual or potential, exist at the sites.   In short, the study assessed the materials found at each site, each source of contaminants at the sites, each relevant pathway (solids, surface water, stream sediments, groundwater, air) by which the contaminants could expose people, animals or the environment.   For each pathway the study then evaluated the likelihood of release of a contaminant to humans or the environment; the waste hazard characteristics, including chemical composition, quantity and relative toxicity; and potential receptors of exposure (human, animal and environmental).   A greater likelihood of release, higher constituent concentrations, or more potential receptors typically would result in a higher score as would the relative risk of the constituent.

It should be pointed out that much of the data analysis, in developing the scores, relied on median values.  The “median” is the “middle” value in a list of numbers (50% of the numbers are above the mean, 50% below) in contrast to the “mean” where you add up all the numbers and then divide by the number of numbers.  What is useful to remember about “median” values is that they sometimes hide extreme sample results more than a “mean” does.  For example, for the Allihies District as a whole, solid waste samples contained a maximum concentration of copper (Cu) at 75,520 mg/kg with a mean of 6,094 and a median of only 2,588; and a maximum concentration of lead at 300,394 mg/kg with a mean of 2,992 and a median of only 33.  Appendix 5, Allihies District, Table 3.  The report concludes that although high concentrations of lead were measured in some samples, in general, as indicated by the median concentrations, lead did not occur in significant concentrations in most samples of solid mine waste analysed for the project, and that “The only element that is consistently measured at high concentrations is Cu (median 2,888 mg/kg; range: <DL – 75,520 mg/kg).”  As an administrative tool to rank sites for the purpose of possible further investigation and remediation, using median values is useful.  When it comes to appreciating the specific site conditions and when planning any investigation and remediation, then the extreme values, indicating hot spots of contamination, do need to be considered.

Another, perhaps related, issue with the report is a certain inconsistency in use of the classification system.  There are five classes of sites, from I to V, with Class I including the sites with the highest risks, namely Silvermines, Tynagh and Avoca, “which should have a full risk assessment carried out” and where “Ongoing monitoring should be carried out.”  The lowest ranked sites are in Class V, which are those sites “not requiring any specific monitoring.”   Sites in the other classes require monitoring on an annual basis (Class II), on a biannual basis (Class III) and on a five yearly basis (Class III).

For some Class V sites, which do not require even any monitoring, the report indicates that there are environmental threats, potential or actual, associated with these sites.  For example, the report for the individual Class V sites at Caminches, Caminches Stamps, Coom, Keeloge, and Mountain Mine, all part of the Allihies District, indicates that “low waste volumes and metal concentrations give rise to a very low site score.”  And then the report adds, “Direct drainage of Cu-rich leachate to local streams appears to represent the most significant potential environmental risk on the site.”  Chapter 5, at pages 78-83.  Elsewhere, the Summaries of the sites and other analyses indicate that copper is consistently found at elevated concentrations (above standards) in water discharging from the mine sites, in stream waters, and in the leachate at the sites.  The report suggests that “Concentrations of Cu in stream sediment are very high downstream of some sites, notably Allihies, Avoca, and, in West Cork, Glandore and Ballycummisk, and the potential impact of this on the aquatic ecosystem at these sites may warrant further investigation.”  At pages 66, 71.  Similarly, the report for the Clare Lead Site at Kilbricken indicates that it has some of the highest concentrations of lead in solid waste at Irish mine sites, and that “A leachate test indicates that there is potential for groundwater contamination in the vicinity of this waste.”  Yet the site is Class V.   At the Abbeytown Site in Sligo, the lead-rich leachate from the tailings pond is entering the estuary at Ballysdare Bay.  At one point the report merely notes this fact (page 155 of the report), while at another point it suggests that this is an issue of concern which should be addressed (at page 24 of the Non-technical Summary).  But again it’s a Class V site.

The seeming paradox — a site classified as requiring no further monitoring that also warrants further investigation — is really a function of the scoring and classification system and how it works in the report, and its limitations, acknowledged in the report.  The report pays a glancing nod toward this problem when, in section 6.3.3, it offers a caveat: the scoring and classification system rank sites and a low ranking does not mean that a particular site is free of “significant health or environmental risks that may need to be addressed.”  At page 151.

While the scoring system is useful as an administrative ranking tool, the actual data at each site needs to be reviewed carefully if one is to appreciate the specific conditions at the sites.  One also wonders what people are supposed to do with data that shows risks and threats at sites but where it is concluded that such sites require no actual monitoring.  Only further monitoring will tell those living near these sites whether the risks have abated or worsened.  Complicating this problem is the fact that the Local Authorities often end up with responsibility for these sites, when the owner has disappeared, and the Authorities lack the funds and expertise to address the significant health and environmental risks.

User-friendly guide

In light of some of the comments above, here is a shortcut user’s guide.  If you want to figure out the implications of the report on a site near you, or a site that you have an interest in finding out more about, go to the individual Summary Site Descriptions in Chapter 5, and the Full Site Reports in Appendix 5.   Don’t forget that the report includes 82 individual sites within 27 mines/districts.  You’ll find a Summary and Full Site Reports on each District and for the individual sites.  Within each Summary, you’ll find some general information on what minerals were worked at the mine, the site’s score and classification (see above), chemicals of concern, and a “Geochemical Overview” which provides the critical levels of contaminants found at the site and some limited assessment of what media are being impacted.  In the Full Site reports, you’ll find a more complete discussion of the history of the district and sites, and all the sampling data.  The Summary descriptions are useful for giving you an overview of all the sites but the Full Site Reports should be consulted if you want to know the details about a particular site.

To appreciate the significance of the levels of contaminants found, you then have to compare the values for the site to the standards provided in chapter 4 on “Geochemical Assessment.”  The relevant standards are drawn from EU, UK, US or other countries, e.g., Netherlands, that have standards for the particular element.  The Summary and Full Site Reports provide results for solid wastes, water, stream sediments, and leachate, and the tables in Chap. 4 provide the relevant standards for soil/solid wastes, water, and stream sediments.  Since little groundwater sampling was practical, the report relies on analysis of leachate as a “proxy” or estimate of the impact on groundwater.   You’ll be able to determine what elements or contaminants are found at the site and whether the level found is in excess of relevant standards.

There is some general background information on all the substances including those which have been found to be carcinogenic or present particular dangers, e.g., forms of arsenic, cadmium, chromium, lead, and mercury.  See Appendix 3, General Geochemical Assessment.  You can then review what substances are found at a site near you and at what level, the relevant standards for the substances, and what generally are risks associated with such substances.   The report, however, does not provide what is typically called a “risk assessment” showing what particular risks are associated with the levels of contaminants found and how much of a risk is presented to people, livestock or the environment.

A Final Word

At the end of the report. the agencies provide a “Non-technical Summary,” a 28-page summary that provides a more readable summary of what the report covers than is usually found in, for example, the Executive Summary, although the later is only 6 pages long.   The language in the Non-technical Summary tends to be, indeed, non-technical and often less abstract than what one typically finds in what is essentially a very technical report, and the visual images, including photo and drawings, are helpful.  Making reports such as this one more accessible to a wider, more general audience is commendable and EPA, and the other agencies, are to be encouraged to do more of this.

SOURCES

The report is found at  www.epa.ie/downloads/pubs/land/mines/

“EPA warns leaks at disused mine facility pose risk to public health,” The Irish Times (1 January 1999).

“Silvermines still under threat from mine waste,” The Irish Times (2 February 2000).

“Dead calf in Silvermines had high levels of lead in system,”  The Irish Times (23 May 2002).

Liam Leonard, Green Nation: The Irish Environmental Movement from Carnsore Point to the Rossport Five (Greenhouse Press/Choice Publishing, 2006).  See, especially, Chapter  7, “Tynagh, Donegal and Croagh Patrick: Campaigns against Mining.”

US EPA Hazardous Ranking System www.epa.gov/superfund/programs/npl_hrs/hrsint.htm