A cantilever wall is to be installed in a granular material which has a unit weight of 118 pcf, a friction angle of 35 d

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A cantilever wall is to be installed in a granular material
which has a unit weight of 118 pcf, a friction angle of 35 degrees.
The height of the wall (H) is 20 ft and the ratio between the top
of the wall the water to the wall height (α) is 0.25. The
ratio of the pile soil friction angle to the soil friction angle
(δ/φ) is -0.7. Using the Caquot and Kerisel lateral earth pressure
coefficients and the chart solution in the “Steel Piling Design
Manual” (USS, July 1984), what is the required
sheetpile section in in^3? Use USS Mariner steel.