Design of Submerged Tanks With Water Table (Tipping Pits)

In design of submerged tanks with detected water table, FLOTATION must be checked aside for stability and overturning. Check for flotation can be done by considering an uplift force caused by the buoyant force. The factor against flotation can be computed by dividing the Total Dead Weight (DWT) of the tank by the Buoyant Force (BF). BF is the weight of the volume displaced using the unit weight of water = 9.81 kN/cu.m from the level of the water table. Acceptable factor of safety against flotation = 2.0 but a 1.5 FS can be deemed acceptable depending on professional judgment.