Aggregate Processing Grizzly Screen

11.19.1 sand and gravel processing - us epa.11/95 sand and gravel processing 11.19.1-1 11.19.1 sand and gravel processing.By dredging involves mounting the equipment on boats or barges and removing the sand and gravel.Which typically is covered with a "grizzly" of parallel bars to screen out large cobbles and boulders.