Use an air/vacuum valve at high points in the line. If possible, design the line so that it has a continuous upward slope in the direction of flow and no high or low points in between the pump and the outlet.
Apco and Crispen are two maufacturers of such valves in North America.
I have designed several low pressure sewer systems and have always specified the grinder pumps to be supplied with anti-siphon valves to prevent the draining of the basin after the pumps shut off. Some maufacturers supply there grinder pumps with the anti-siphon valves standard in the Basin and others have modified there standard models to conform with the specifications.
