This guide describes standard operating job procedures for the primary sedimentation process of wastewater treatment plants. The primary sedimentation process involves removing settleable and suspended solids, in part, from wastewater by gravitational forces, and scum and other floatable solids from wastewater by mechanical means. Step-by-step instructions are given for pre-start up procedures, start-up procedures, continuous operating procedures, and shut-down procedures, along with a description of the equipment used in the process and some theoretical information. (BB)