This report completes the study on package plants. The purpose of this phase of the study was to develop performance criteria for contact stabilization type package sewage treatment plants. It should be emphasized that the data which appears was collected during the period of criteria development and not under necessarily normal operating conditions. It was found that operation of these plants indicated that this process can satisfactorily remove the major portion of both suspended solids and the bio-chemical oxygen demand in domestic wastewater without the creation of an odor or noise nuisance in the surrounding area.