A separation tank with an outer chamber and an inner chamber within the outer chamber. An inlet and outlet are formed in the outer chamber to receive and discharge water, respectively. An inlet opening is located in the inner chamber and is generally aligned with the inlet to receive water from the inlet. An outlet opening is formed in the inner chamber below the inlet opening but above the bottom of the inner chamber. The inner chamber has a cylindrical interior surface such that water from the inlet is directed at a tangent to the interior surface and forms a vortex as the water progresses through the inner chamber. A baffle plate having an opening forming upper and lower weirs is located within the outer chamber just upstream of the outlet to separate both floatable and non-floatable material from the water prior to its discharge.