If your house is in an area that uses grinders, it's like having your very own mini pumping station. SCCLSD utilizes over 100 simplex (1 pump) and over a dozen duplex (2 pumps) grinder pump stations.
Typical Simplex Grinder. Illustration courtesy of Fluid Kinetics, Inc.
Your sewage leaves your house just like both of the aforementioned methods, by means of a lateral connection, but instead of connecting to a sewer main or a vacuum valvepit, you connect to a grinder tank. The grinder tank is a small version of a wetwell for a gravity pumping station. It collects your sewage and maybe your neighbors, grinds up the solids, and then pumps it to a gravity sewer through a small pressure collector line. The idea of grinders is to service low lying areas and small areas where it would not be cost effective to install gravity or vacuum sewers.