A clay layer underlies a $12$ m thick silty sand, and a sheet pile is driven into the sand $($figure below$).$ The permeability of the silty sand is $8\mathrm{.}610-4$ cm$/$s$.$ The clay can be assumed to be impervious. The void ratio of the silty sand is $0\mathrm{.}72$ and the Gs is $2\mathrm{.}65.$ a$)$ Draw a flow net by hand and estimate the seepage beneath the sheet pile in m$3/$day per meter length of the sheet pile b$)$ Calculate uplift pressure beneath the sheet pile c$)$ Calculate the factor of safety against piping