Given below, a flow net in an isotropic silty soil layer overlying an impervious layer. Knowing that $k={0\mathrm{.}5}^{**}10-4c\frac{m}{s},sat=19K\frac{N}{m}3,w=10K\frac{N}{m}3,$ Find:

a$)$ The total rate of seepage through the permeable layer per unit length

b$)$ The pore water pressure at points a$,$ b$,$ d$,$ e$,$ f and h

c$)$ The exit gradient then deduce the factor of safety against piping at exit. Comment.