f any regard for the bay and the surrounding environment. The current plant is the result of the 1972 Clean Water Act and several lawsuits filed by the Environmental Protection Agency against the city of Los Angeles in 1977. The new legislation forced the city to take into account the surrounding biotic communities and to construct new more environmentally sound facilities. The City of Los Angeles was forced to stop dumping sludge into the ocean and to provide full secondary treatment for all wastewaters. (WFPU I 2)The current plant process starts with preliminary treatment to remove any large floating items from the raw sewage. This treatment would remove items such as rags, boards, and other inorganic items which if allowed to pass could cause significant damage to the system. This phase of treatment is also designed to remove or reduce large suspended solids, floating inorganic solids, and dense inorganic solids like sand or metal. The amount of sewage entering the plant is also measured at this point using flow-metering equipment. Any large organic solids removed at this stage get hauled to a sanitary landfill. Materials known as grit (sand, gravel cinders, bone chips etc.) are removed at this stage by means of aerated grit chambers. These chambers allow heavier solids to settle to the bottom while lighter usually organic solids remain in suspension. The grit removed at this stage is also sent to a landfill after it has been washed. After this preliminary treatment the wastewater still contains a fair amount of suspended solids. Primary clarifiers are used to remove some of these solids. The primary clarifiers allow the wastewater to flow from one end to the other. A hopper removes the sludge that settles on the bottom. The surface grease and oil is collected by a surface skimmer and removed from the tank. The primary clarifiers remove about 65% of the total suspended solids in the wastewater. After primary clarifica...
