A liner designed to prevent contaminants from moving vertically downwards from a landfill and into the underlying aquifer consists of two layers, as shown. Each is half a metre thick. A piezometer inserted at point x shows a pressure head of 0.5 m. A piezometer inserted at point Y shows a pressure head of 0.4m. a) If the liner has an area of 15ha, how much water passes downwards through the landfill liner each day