Organic matter content influence on the hydraulic properties of sandy material

Abstract The performance of the cover system, used in the reclamation of a mine site, is primarily assessed through hydraulic properties, including volumetric water content, suction, and saturated hydraulic conductivity ( k sat ). However, these properties may be influenced by factors such as soil mineralization (which refers to the process by which organic materials are converted into inorganic substances through natural processes), temperature (by the viscosity of water and the activity of microorganisms in the soil), and organic matter content (OMC), which complicate the accurate assessment of cover system performance. To better understand the impact of OMC on hydraulic properties, this study was initiated with two objectives: (i) evaluating the effect of OMC on the water retention curve (WRC) and k sat of a sandy material amended with peat and (ii) proposing equations to predict the WRC of sand amended with organic matter using the Fredlund and Xing model. This was accomplished through laboratory tests that determined the WRC and k sat of sand and sand amended with varying concentrations of peat (0%, 1%, 3%, 5%, 7.5%, 10%, 12.5%, and 15%). The investigation results indicate the air entry value (the suction at which the material begins to desaturate) evaluated using the sand mixture WRC did not show any notable variation. The k sat of the sand mixtures decreases with increasing peat concentration. In terms of prediction, the results obtained for the six mixtures tested in the laboratory showed an excellent agreement between predicted and experimental values, demonstrating the high accuracy with which the WRC s were predicted.