A consolidation test performed on a sample from mid$-$depth of the clay layer results the following:

initial void ratio $=0\mathrm{.}6$

coefficient of re$-$compression $=0\mathrm{.}025$

coefficient of compression $=0\mathrm{.}224$

preconsolidation stress $=3000psf.$

coefficient of consolidation $=0\mathrm{.}065f\frac{t^2}{?}$ day

a$)$ Calculate the primary consolidation settlement of the clay layer due to the proposed fill.

b$)$ Find the time it takes to complete $90\%$ of the estimated primary consolidation settlement.

c$)$ Estimate the change in height of the Fine silty$-$sand $($SP$-$SM$)$ layer due to the fill.