The system is not setup 100 percent correct. The piping coming out the top should be for discharge and venting only, the waste inlet to the system is underground ( waste should enter through the side of the pit). The laundry tray/laundry sink is draining into the vent port of the system. I think the system is pipe this way-- The waste inlet is being used as a vent (meaning the cast iron under the sink is attach to the pit waste inlet).The pvc pipe tied to the cast iron pipe coming out the floor is a vent that has been ran above the cinder block to the exterior of the house or quick vent. The vent port of the pit is being used as the laundry waste inlet then revent to the vent. The discharge is what it is. I'm just assuming this is the configuration looking at the pics and not being there.