A square footing with 5-ft sides is located 4 ft below the ground surface. 4 ft Cohesive Soil y = 120 lb/ft qu = 3000 lb/ft 5 ft Estimate the total quantity of the soil in terms of weight and volume to be excavated including the provision of a 2 ft thick sand-gravel cushion. How much quantity of sand-gravel cushion with a density of 130 lb/ft would be required if a 2 ft thick layer is to be placed below the foundation?