In a sandy soil (' = 35; = 18.0 kN/m 3 , and sat =

In a sandy soil (ϕ' = 35°; γ = 18.0 kN/m³, and γ_sat = 20.0 kN/m³), the water table is located at a depth of 6 m below the ground level. How deep would you drive a sheet pile to carry out an excavation to 4.0 m depth? Use the simplified approach discussed in Section 18.8, with a factor of safety of 1.5 on passive resistance (i.e., use K_p/1.5).