4.7 An 80-mil (2-mm) HDPE geomembrane with an allowable stress of 1,300 lb/in² (9,000 kN/m²) rests on a 3(H):1(V) sidesl

[answerhappygod]

4.7 An 80-mil (2-mm) HDPE geomembrane with an allowable stress
of 1,300 lb/in² (9,000 kN/m²) rests on a 3(H):1(V) sideslope. A
30-inch (0.75-m) thick cover soil with a unit weight of 110 lb/ft³
(17.3 kN/m³) (also the unit weight of the backfill soil) is placed
over the geomembrane. The friction angle between the geomembrane
and soil is 15 degrees and that of the soil itself is 30 degrees.
Make the runout length equal to 60 inches (1.5 m), and the depth of
anchor trench the same as the width of anchor trench. Calculate the
depth and width of an L-shaped rectangular anchor trench.