A sheet pile wall is driven into a horizontal bed of silty sand and shown in Fig. $5\mathrm{.}36,$

in order to impound a maximum depth of $5$ m of water. The concrete apron is to

be laid to reduce the seepage loss. The coefficient of permeability of the silty sand

is $7\mathrm{.}5{10}^{-6}\frac{m}{s}.$

$($a$)$ Sketch a flow net and from it estimate the maximum seepage quantity in $\frac{m^3}{hr}$

per metre run.

$($b$)$ Plot a curve showing the maximum hydrostatic uplift pressure distribution on

the concrete apron.

Fig. $5\mathrm{.}36$