Effectiveness of Soil/Spoil Amendments in Minimising Adverse Impacts of Runoff and Erosion at Coal Mine Rehabilitation Sites in the Bowen Basin Region, Central Queensland

Abstract

Effects of vegetation cover on runoff and soil loss reduction at mine rehabilitation sites are well documented. However, the knowledge of soil amendment applications, namely polyacrylamide (PAM) and gypsum, prior to the establishment of vegetation is still very limited. These soil amendment methods have proven to have the ability to improve soil surface stability in agriculture, however, the application of soil amendments to improve the spoil surface at mine rehabilitation sites is still un–trialled and their effectiveness largely unknown. This study covers 4 topics namely; (1) to analyse the effectiveness of soil amendments towards improving the hydraulic conductivity of the soil and spoil; (2) to determine the effect of soil amendments application on sediment concentration in the runoff and total soil loss generated from the laboratory based soil erosion experiments; (3) to assess WinSEADS model (Soil Erosion and Deposition Simulation – Windows) to predict sediment concentration and total soil loss under a variety of scenarios; (4) to carry out cost assessment of possible field application of soil amendments under several scenarios. In the small–scale experiments, the application of soil amendments to the soil and spoil was found to be beneficial in increasing the hydraulic conductivity. The results indicate that gypsum is more effective in maintaining a high hydraulic conductivity when compared with PAM. The percentage increase of hydraulic conductivity was found to depend on the soil amendment application rates; and the physical and chemical characteristics of the soil and spoil.