Abstract: A separator apparatus for separating flush effluent from an oil and gas well following a fracture stimulation process, the separator having a vessel that maintains the effluent at a selected liquid level, an inlet is connected to the vessel at a location below the liquid level so that the effluent enters the vessel at a location therebelow. A plurality of baffles within the vessel slow the effluent so that solids settle out to a drain which is periodically opened to transfer the solids to an appropriate disposal. An upper outlet permits the venting of gases that percolate from the liquid constituent, a backpressure valve disposed in communication therewith to maintain a positive pressure within the vessel. A liquid drain withdraws the liquid constituent from the vessel at a rate determined by a level assembly.