Three options are being reviewed for the foundation for an offshore wind turbine $($Figure $1).$

Option $1$: Monopile composed of a steel hollow driven pile that is $20m$ long. The monopile is circular having diameter of $6m.$

Option $2$: Tripod composed of three steel hollow driven driven piles that are $20m$ long, and spaced on a triangular grid at $5m$ centres $($Figure $1).$ The piles are circular having diameter of $1m.$

Option $3$: Caisson foundation composed circular footing having diameter of $6m$ and embedded $1m$ into the seabed.

The site investigation reports indicated that the seabed is composed by a layer of loose sand $)=21k\frac{N}{m^3},{}_{\text{p}\text{e}\text{a}\text{k}}=30,{}_{cv}=(27$ and at $18m$ depth a layer of clay $)=(18k\frac{N}{m^3}$ was identified with an undrained strength, $C_u$ of $15$kPa $($see Figure $1).$ The water depth at this location is $7m.$

Note: Assume that for $4\frac{\text{I}}{D}10$ the depth correction factor $d_c=1\mathrm{.}3.$ For steel driven piles you may assume $$~~$cv.$ For hollow piles you may neglect the end bearing component.

Figure $1.$ Side view diagram for Question $2.$