QUESTION $2,(25$ marks$)$

A concrete retaining wall, which is founded on rock, is retaining $7$ m of ground as shown in Figure $3.$ A hydrostatic groundwater table is present on the retained side at the interface between the Loose Sand and Dense Sand layers. The design parameters are as follows:

$\backslash$table$[[$Water$,$Density, ${}_w=10k\frac{N}{m^3}$