Steel storage tanks as used by refineries and storage companies for the storage of liquids, are rarely constructed on piled foundations.   They are placed on foundations which are constructed of sand, or crushed stone, or a combination of both.  Usually the tank foundation is raised some 50 to 100 cm above ground level.

If the sub soil is weak and easily compressed, then settlement of the foundation under the tank may occur. These settlements can occur evenly or unevenly.  If the settlement becomes excessive then problems may arise with the floating roof, the bottom, and the pipes to and from the tank.  If the tank settles below ground level then corrosion may occur as a result of contact with water.

In each of the above cases the foundation need to be reinstated to an acceptable level.  The tank must then first be re-leveled and brought to the required height of level.