A soil having the average properties, bulk unit weight $=19 \mathrm{~kN} / \mathrm{m}^3$; angle of internal friction $=25^{\circ}$ and cohesion $=15 \mathrm{~kPa}$, is being formed on a rock slope existing at an inclination of $35^{\circ}$ with the horizontal. The critical height (in $\mathrm{m}$ ) of the soil formation up to which it would be stable without any failure is __________ (round off to one decimal place).
[Assume the soil is being formed parallel to the rock bedding plane and there is no ground water effect.]