A borehole at a site reveals a soil profile comprising 6 m deep fine sand layer overlying a 9 m thick clay layer, which in turn overlies weathered bedrock. The groundwater table is located at a depth of 4 m from the ground surface. A zone of capillary saturation exists in the fine sand layer above the groundwater table. Above the zone of capillary saturation, the fine sand layer can be considered to be dry. The air entry value (AEV) for fine sand layer is 15 kPa and its specific gravity (Gs) and porosity (n) are 2.65 and 0.315, respectively. The natural water content (w) and void ratio (e) of the clay layer are 28.5% and 0.7, respectively. The unit weight of water (γw) is equal to10 kN/m3

a. At what depth from the ground surface is the top of the capillary saturation zone located?

b. Calculate and plot the distribution of total and effective vertical stresses as well as pore-water pressure with depth from the ground surface up to the bedrock surface.