Question $4(25$ Points$)$

In the soil profile shown below, Point A is at elevation of $200ft$ above sea level, point $B$ is at elevation of $193ft,$ point $C$ is at elevation of $183ft,$ point $D$ is at elevation of $163ft$ and point $E$ is at elevation of $160$ feet respectively. Development at that site is imposing a stress of $5000l\frac{b}{f}{t}^2$ as shown in the diagram.

Calculate the following:

$($a$)$ The total vertical stress, pore water pressure and effective vertical stress at elevations $200ft,190ft,185ft,180ft$ and $160$ feet above sea level respectively.

$($b$)$ If water rises above the ground by $35ft,$ calculate the effective stress at elevation $160$ feet above sea level.