The following images and text provide an overview of the treatment process. To arrange an actual tour of the plant, call Mark Rogers, the District's Treatment Supervisor, at (805) 684-7214 x18. Influent Pumps. Wastewater entering the plant is pumped up so that it can flow through the treatment process and out the outfall pipe entirely by gravity. Screening and Grit Removal. A self-cleaning mechanical bar screen removes rags, floatable debris and other oversize material. A cyclone grit separator then removes sand, gravel, egg shells and other non-organic components of the incoming wastewater. Screenings and grit are disposed of in a permitted sanitary landfill.