Garvie, A, Donaldson, K, Williams, B & Chapman, J 2019, 'A demonstration of the cessation of spontaneous combustion in a coal overburden spoil pile', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 897-910, https://doi.org/10.36487/ACG_rep/1915_71_Garvie
(https://papers.acg.uwa.edu.au/p/1915_71_Garvie/)
Abstract: Leigh Creek Coal Mine is located in South Australia approximately 550 km north of Adelaide and operated between 1944 and 2015. During operations, localised spontaneous combustion occurred on numerous occasions in the overburden spoil piles containing relatively small volumes of coal (about 0.8%). The majority of the overburden sequence consisted of sandstones and carbonaceous mudstones. Samples of overburden rocks had total sulfur and total organic carbon present at up to 2.2 and 14 wt% respectively. At the end of mining, localised surface temperatures of up to 200°C were measured.
Laboratory testing demonstrated the potential for self-heating and spontaneous combustion of both coal and overburden material in the spoil piles. The management strategy selected for preventing spontaneous combustion in the post-closure period included:
A trial of the management strategy was established in June 2017 in a location that was actively combusting. The batter slopes of the area were reduced, and an inert cover was placed over the area. Measurements of temperature, oxygen and carbon dioxide concentrations in the spoil pile over 20 months show that:
Spoil pile conditions before and after the implementation of the management strategy are presented and an assessment of the effectiveness of the management strategy is provided.	

Keywords: spontaneous combustion, overburden spoil pile, temperature, gas concentration, permeability, mitigation strategy, closure