A clay layer 24 metres thick has a saturated unit weight of 18 kN/m3. Ground water level occurs at a depth of 4 metres. It is proposed to construct a reinforced concrete foundation, length 48 m and width 12 m, on the top of the layer, transmitting a uniform pressure of 180 kN/m2. Determine the settlement under its centre. E for the clay is 33 MN/m2 obtained from triaxial tests. Initial void ratio = 0.69. Change in void ratio = 0.02.