Infiltration tests in dry covers experimental models using coal ashes from Pecém thermal power plant

ABSTRACT The significant amount of coal ashes stored in Energia Pecém Thermoelectric Plant adjacent yards required researches that propose ways of applying this waste, allowing their correct final disposal. Application of this material in dry covers systems proved to be a viable alternative, due the former experience in other works and the possibility of absorbing a large amount of the ashes produced. This work corresponds to second part of a research that studed the application of coal ashes in engineered sanitary landfills dry cover systems. Considering data of a preliminar numerical modelling analysis, three soil columns was builded, which represented three different dry cover systems: Column A – A natural soil layer (30 cm) and a waterproof layer composed of the soil and ashes mixture M70C30 below (30 cm, composed by 70% soil and 30% ashes); Column B – A natural soil layer (30 cm) and a waterproof layer composed of ashes (30 cm) and Column C – A single layer composed of natural soil (30 cm) reproducing the dry cover adopted in Caucaia Municipal Sanitary Landfill. The Column A was instrumented with three moisture sensors. For each column were executed two infiltration tests, measuring the percolated water volume. Furthermore, the saturation profile of the instrumented column (Column A) was obtained in the two tests. The resulting data of the experimental model demonstrated that de system with the MS70C30 mixture in the waterproof layer presented the best performance when analysing the reduction of water flux. The percolated water volume measured in this case was much lower than that obtained for the other two columns. The same material managed high levels of saturation, over 90% during almost the entire duration of tests, necessary condition to reduce biogas diffusivity in the system.