Abstract: A portable wash water containment apparatus having a flat ground cover portion surrounded by an integral berm formed from the ground cover material, said berm defines the area of the apparatus in which contaminated are contained. Dual ramp assemblies are provided to allow ingress and egress from the containment mat without damaging the berm or ground cover portions. A pump system is included to provide oil/water separation before discharging waste water into a sewer system. The containment mat may also be equipped with electrical heating elements to facilitate use in extreme cold temperatures.