A municipal landfill was constructed ten years ago with a base liner consisting of 0.3m of local clay. Samples of this clay have been found to have a hydraulic conductivity of 1.0 x 10-9 m/s and a porosity of 0.4. The underlying soil is a fine sandy soil, also of porosity 0.4, on top of a chalk aquifer. Assume that the concentration of the contaminant within the landfill remains constant, the flow is vertical, and the hydraulic potential difference across the clay liner is 0.9 m. Take Dd* = 1.0 x 10-9 m2 /s. Estimate the current depth of penetration of solute contaminant from the landfill for (i) advection only; (ii) diffusion only.