Abstract: A system is described for improving separation of sewage containing wastewater, oleaginous materials and solids. The system includes a tank 10 having a first chamber 12 and a second chamber 14. In the first chamber oleaginous materials rise to an upper portion thereof and a grinder pump 30 grinds the solids that descend toward the bottom of the first chamber. The second chamber in communication with the first chamber delivers the sewage to a discharge line 24 in communication with a transport line that leads to a downstream sewage treatment plant. A conduit 32 conducts the slurry of the ground solids from the first chamber to the discharge line. A pressure relief line 40 running from the conduit releases the head pressure into the first chamber. The pressure relief line is connected to the conduit downstream of the conduit's highest point of elevation.