We have a submerged holding tank for toilet and sink waste coming from a basement apartment. Every time the tank empties, there is a loud bang when the pump stops. It seems that the pipes shake, and we are concerned that this will stress the system. Is this normal, and if not, what can we do to stop this?

In your sump system is a 2" valve just above a 2" check valve. As the water exits the sump by way of the pump it is pushed up hill. The check valve is there so the water will not all drain back into the sump basin and kick the pump back on. It is normal what you hear, but secure the piping because loose piping moves and moving piping breaks something or leaks.