A footing of size $2\: m \times 2\: m$ transferring a pressure of $200\: kN/m^2$, is place at a depth of $1.5\: m$ below the ground as shown in the figure (not drawn to the scale ). The clay stratum is normally consolidated. The clay has specific gravity of $2.65$ and compression index of $0.3$.
Considering $2:1$ (vertical to horizontal) method of load distribution and $\gamma_w= 10\: kN/m^3$, the primary consolidation settlement in (in mm, round off to two decimal places) of the clay stratum is ________.