A method of evacuating a refinery tank containing waste with solid constituents is disclosed. The method includes inserting an agitator on a boom through a first opening on a side of the refinery tank and agitating waste in a first area of the refinery tank to cause the waste in the first area to have a first viscosity lower than a second viscosity of waste in a second area at a periphery of the first area. The method further includes removing agitated waste from the first area while maintaining the waste of the second viscosity in the second area, thereby forming a safe room in the refinery tank. The method also includes expanding the first opening toward the floor of the safe room to enable entry of a movable excavator into the safe room of the refinery tank and removing waste of the second viscosity from the second area of the refinery tank.