Abstract: An apparatus and process for separating contaminants from particulate material for separating undesirable debris from particulate material such as sand or gravel quickly and efficiently for increasing the production of separated gravel. A conveyor having a frame and a belt with corrugated side walls defining a channel for retaining water. The conveyor includes a second roller adjacent a rear portion of the conveyor, wherein a cornice of the second roller is preferably at an elevation equivalent to an upper edge of the corrugated side walls. At least one dividing member having a front edge, wherein the front edge projects into an upper layer of water within the channel for separating the upper layer from a lower layer of the water. Water is supplied to the channel adjacent the rear portion and a mixture of contaminated rock is supplied thereafter through a delivery chute.