An apparatus and method for separating oil and particulate contaminants from pump-driven aqueous fluid contaminated with emulsified oils, free oils, particulate matter, suspended solids, and other contaminants in which the contaminated fluids are introduced into a container having a horizontal bottom portion and a weir plate dividing the container into an upper clean fluid compartment and a lower separation compartment, an aperture for the outflow of clean fluid from the upper clean fluid compartment sized relative to the pumping rate of the pump driving the aqueous fluid to ensure a residence time of the contaminated fluid in the lower separation compartment of at least about 0.4 minutes, coalescing media comprising a plurality of abutting polypropylene spheres located in the lower separation compartment, and a drain receptacle for collecting the contaminated fluid and delivering the contaminated fluid across the weir plate to the lower separation compartment.