Schier Products Co. offers the Great Basin™, an engineered thermoplastic grease interceptor with dry inlet and capacities from 150 to 500 gpm. The basin is made of heavy-duty polyethylene (1/2-inch-thick walls) and is designed for above- or below-grade installations (interior or exterior). Inlet and outlet diffusers create a unique flow pattern, allowing grease to collect at the surface, sediment to drop and gray water to pass through. It does not require an external flow control fitting. With three outlet options on each tank, multiple footprint configurations can accommodate limited space requirements. Schier Products Co. Circle 8.