A 22 m thick normally consolidated clay layer has a load of 150 kPa applied to it over a large areal extent. The clay layer is located below a granular fill (ρ = 1.8 Mg/m3) 3.5 m thick. A dense sandy gravel is found below the clay. The groundwater table is located at the top of the clay layer, and the submerged density of the soil is 0.95 Mg/m3. Consolidation tests performed on 2.20 cm thick doubly drained samples indicate t50 = 10.5 min for a load increment close to that of the loaded clay layer. Compute the effective stress in the clay layer at a depth of 16 m below the ground surface 3.5 yr after application of the load.