Environmental Risk Issues at a Coal Waste Spoil Heap—Climate Change Concern ^†

Abstract

The aim of this study was to identify potential factors related to weather changes and their impact on the coal waste spoil heap. Risk analyses were performed for selected sites using an “if–then” method for the construction of future scenarios, and a risk evaluation matrix for each predicted scenario was determined. The results showed that some of the factors may be ambiguous. For instance, more intense rainfall may cool the material in the heap and reduce the fire risk. On the other hand, it can lead to surface erosion and oxygen access to the material, which may increase the fire risk.

1. Introduction

Climate projections for Europe under different Representative Concentration Pathways (RCPs) provide valuable insights into potential future scenarios. Three parameters are crucial temperature, wind velocity, and precipitation. Meinshausen et al. [1] highlight that under RCP2.6, the global mean surface temperature increase by 2100 could be around 1.5 °C, while under RCP8.5, it could reach 4.5 °C relative to pre-industrial levels. Further elaborating on temperature projections, increases ranging from 0.9 to 2.2 °C for RCP4.5 and 1.4 to 2.7 °C for RCP8.5 are indicated to occur by the mid-century, focused around 2055 compared to baseline (1981–2020). The North Atlantic atmospheric circulation patterns, such as the North Atlantic Oscillation, East Atlantic, and Scandinavian patterns, have been identified as influential on the European wind climate at seasonal to inter-annual scales, especially over Western Europe [2]. It has been suggested that the frequency of extratropical cyclones in Northern Europe will align with changes in the storm track regions, leading to alterations in the wind climate [3].

For Poland, according to RCP4.5, the average annual temperature in Poland will increase by 1.3 °C during the current century. According to RCP8.5, the upward trend in average annual temperature is much stronger. Considering projections of precipitation in Poland for the RCP4.5 and 8.5 scenarios, in both cases, the trend is upwards, and rain intensity may be increased.

Coal waste spoil heaps result from mining activity, and they are the subject of wide research, especially due to environmental issues [4]. A spoil heap influences the atmosphere, water, and soil, and the process is expected to be significantly long-term.

Considering future variations in the three crucial meteorological parameters, the influence of climate change on a spoil heap is shown below. An increase in air temperature increases the fire hazard (caused by the spontaneous combustion of coal). Stronger winds make it easier for oxygen to access a spoil heap, which intensifies the self-combustion risk. In addition, stronger winds make dusting and gas emissions more intense. Floods due to runoff from abandoned spoil heaps during heavy rainfall events are expected. Therefore, it is anticipated that this risk will increase due to climate change. Furthermore, it will be a particular issue in those geographical areas where mines are still active, or where closure has occurred recently, so remediation measures such as vegetation, which could mitigate against runoff, are not yet sufficient [5].

However, an analysis of some important factors indicates that their change may have an ambiguous impact on the environmental hazard associated with the heap and crucial examples have been demonstrated in the text.

2. Materials and Methods

Risk identification is the generation of a complete list of risks based on those events or effects that might create, enhance, prevent, degrade, accelerate, or delay the achievement of objectives that are established in the context. In health and safety terms, these events are hazards; in environmental terms, they are impacts [6]. Climate risk management is an approach which looks specifically at climate risks as part of a comprehensive risk management strategy. The risks range from extreme weather events, such as storms and floods, to slow-onset environmental changes such as increasing sea levels and desertification. Risk management in mining areas, especially connected to extreme weather events, allows decision makers to develop specific actions (strategies) that are relevant to safe and economical operating conditions in situations of exposure to a defined hazard, which is often detrimental or harmful [7].

Based on work carried out in the TEXMIN project and a review of the scientific data, we identified climate risk factors (water, temperature, pressure) directly related to climate change and the occurrence of extreme climatic events. The SWIFT technique was used (“IF” and “THEN” formula). Then, the factors were defined with reference to mining coal mining spoil heaps. An example of a selected factor set for a coal waste heap around south Poland is shown in

Table 1. Various perspectives for a single risk factor.

Factor	Direction of Change	Risk	Impact
Rainfall	Increase	IF rainfall increases, THEN increased water erosion may appear at the surface of a spoil heap	Increase in the number of gaps and gullies at the surface leading to more intense oxygen access
Rainfall	Increase	IF rainfall increases, THEN increased water erosion may appear at the surface of a spoil heap	Cools down the burning waste
Temperature	Increase	IF temperature increases, THEN an increased risk of spontaneous combustion is expected	Increase in the number of fire accidents and increased rate of gas emissions

. It shows various perspectives for a single risk factor.

Then, a risk matrix was developed for the years 2020 and 2050 (considering the worst RCP 8.5 scenario). The risk matrix was based on a common combination of probability and consequence [8]: Probability is assigned in the range 1–5, where 1 is rare, 2 is unlikely, 3 is possible, 4 is likely, and 5 is almost certain. The consequence values are also in the range 1–5, where 1 is negligible, 2 is minor, 3 is moderate, 4 is major, and 5 is catastrophic.

Risk is set in the range between I and V, where I is very high, II is high, III is medium, IV is low, and V is irrelevant.

3. Results and Discussion

The example of the analysis and the results are given in

Table 2. Examples of an ambiguous impact on the environmental hazard—risk evaluated for 2020 and 2050.

Risk Factor	Probability in 2020 (1–5)	Probability in 2050 (1–5)	Consequence	Risk in 2020	Risk in 2050
IF rainfall increases, THEN increased water erosion may appear at the surface of a spoil heap	3	5	3—for increase in gaps and gullies at the surface leading to more intense oxygen access	III	II
IF temperature increases, THEN increased risk of spontaneous combustion is expected	3	5	3—for increase in the number of fire accidents and increased rate of gas emissions	III	II

. The selected example due to rainfall shows that a single risk factor should be considered in different aspects. The example due to temperature is clear and one-dimensional.

These results lead to the following observations and conclusions. The variations in risk for the two most important factors, temperature and rainfall, are presented. In both cases, the change in the probability of occurrence in the 2020 and 2050 stalemates was analyzed. The probability in 2020 was determined as possible, and in 2050, as almost certain, in accordance with the predicted RCP scenarios.

Although the factor of rain is crucial and strong water erosion is expected, it can also be expected that very intense rainfall may lead to the partial cooling of the material on the heap (Table 1). Therefore, for this factor, the consequence was assumed to be moderate.

For temperature, the consequence was also determined to be moderate as a change in mean annual temperature of a few degrees Celsius is expected.

However, the most important conclusion resulting from the analysis presented in Table 2 is that in the case of both factors, the risk is expected to increase from III (medium) to II (high).