There are several types of tank that store hazard materials on coastal area. In order to restrain the spread of spilled contents, those structures are regulated by the building code to construct a weir around them. The weir structure sometimes produces quite complex flows, such as wave overtopping and wave runup with large vortex, inside and round the weir. Further, these complex flows overtopping the weir may also produce specific hydraulic pressures and forces inside the weir, which resulting to the additional damage on the structures. This study investigates the character of wave surface elevation, velocities, pressures and forces acting on the cylindrical structure, which is surrounded by a wall that is modeled on an oil weir. The effect of weir configuration, i.e. height and diameter, to the wave pressures and forces were also discussed.