4. A wide embankment fill (y = 19 kN/m) is constructed on a 15 m thick clay layer resting on an impervious rock stratum. The clay layer is soft and normally consolidated. A 1 m thick sand blanket (y = 18 kN/m) is laid on the entire top surface of the clay layer and below the embankment fill. A representative sample from the clay layer is tested in an oedometer for a stress increment equal to that imposed by the sand blanket and the embankment fill together. The clay specimen's thickness was 20 mm initially, and its thickness decreased by 8% at the end of the primary consolidation process. The time taken to reach 90% consolidation of the specimen is found to be 17 minutes. (a) Determine the consolidation settlement in the field due to the sand blanket and the embankment fill when the excess of pore-water pressure in the clay layer is zero and find the coefficient of consolidation for the vertical flow from the oedometer test