Laboratory investigations were conducted to assess the unsaturated hydraulic conductivity of foundry sand waste treated with up to 8% bagasse ash (a pozzolana) by dry weight of soil. Specimens were prepared at molding water contents -2, 0 and +2 of the optimum moisture content using the four energy levels of reduced British Standard light, British Standard light, West African Standard, and British Standard heavy. The predicted unsaturated hydraulic conductivity of specimens were determined using the Brooks-Corey (BC) and Van Genuchten‟s (VG) models from results of the soil water characteristic curve (SWCC). The unsaturated hydraulic conductivity decreases with increasing matric suction for both models. While the unsaturated hydraulic conductivity decreases with increasing moulding water content regardless of the compactive effort and bagasse ash content. The VG model gave a clearer trend as regarding the influence of increasing bagasse ash content of the unsaturated hydraulic conductivity of treated and untreated specimen. Finally, 2% and 4% bagasse ash treatment of specimens were the main treatment level of interest gave satisfactory for use in covers for waste containment facility as the unsaturated hydraulic conductivity values generally recorded satisfactory low values.