The 3 in 1 Feed System can virtually handle any solid feed material problem in a closed loop process. This feed system enables thermal treatment to proceed, eliminating multiple handling steps, extra equipment and personnel that often add time and expense to treatment operations. In stage one, soil is scalped through a hydraulic tipping grizzly section. Soil passing the grizzly enters the feed hopper, which has steep sides to promote flow of highly plastic soils. The material is drawn out of the hopper and sliced on a variable speed, bar chain drag slat feeder. Material passes through an electric metal detector. As metals are detected, operations stop automatically so scrap metals can be removed. Stage two consists of an inclined single deck screen to separate oversized from sized particles. Material passing this screen goes into a surge hopper and is fed by a bar chain feeder to the thermal processor. Oversize material drops to a reversible cross conveyor which gives the operator the choice of rejecting oversize particles or sending them on to stage three. Stage three is an impact mill equipped with air blasters that can shred clay or crush solids such as rock. Discharged material from the crusher falls on the original gathering conveyor to be returned to the sizing screen for final separation.