Los Angeles County's nine million residents use the Bay for a wide variety of purposes, including the discharge of treated domestic, commercial and industrial wastes. Currently about 645 million gallons of treated municipal wastewater are discharged to the Bay by the region's two major sewage treatment systems.
Although municipal wastewaters have been a significant source of contaminants to the Bay, extensive and continuing improvements in treatment processes and stringent industrial waste controls have reduced contaminant levels to a fraction of former levels. Effects of wastewater outfalls on surrounding fish and invertebrate communities are still noticeable, however environmental monitoring programs show that these marine life communities are beginning to resemble those in more pristine areas. Nonetheless, future population and economic growth could offset these gains unless a continuing, comprehensive pollutant reduction strategy is implemented.
Water pollution is classified as coming from two separate types of sources: point and nonpoint. Nonpoint sources are generally more diffuse, and include runoff from housing and commercial developments, industrial sites, roadways and parking lots. Pollutants associated with these sources include pesticides, fertilizers, silt and sediment; chemicals (such as motor oil and antifreeze) that drip from motor vehicles onto driveways and streets, and pet wastes.
The 1972 version of the Clean Water Act focused on cleaning up "point" sources like chemical discharges from factories and effluent from sewage treatment plants, because large discharges were easier to identify and control. The National Pollutant Discharge Elimination System (NPDES) regulates point source emissions, and recent Clean Water Act amendments have broadened federal and state mandates to reduce non-point pollution sources.
Pipes or outfalls from municipal wastewater plants, power plant cooling water discharges, and industrial waste effluent are point sources. There are seven major point source facilities in the Santa Monica Bay watershed: three municipal waste treatment plants, three coastal generating stations, and one oil refinery. In addition, over 160 smaller commercial and industrial facilities discharge non-process wastewaters to storm drain channels that flow to the Bay.
Each major point source facility has a variety of responsibilities for managing wastewater discharges. All must meet requirements set forth in their NPDES permits, monitor their discharges for compliance with their permits, and submit monthly reports to the Los Angeles Regional Water Quality Control Board (LARWQCB) and the U.S. Environmental Protection Agency (EPA).
Municipal wastewater facilities receive sewered wastes from domestic, commercial, and industrial sources. Residential wastewater (sewage) contains a variety of household cleaners and detergents; oil, grease, and solvents; food wastes; and enteric (intestinal) bacteria from human fecal waste. It is estimated that each person in the region generates approximately 100 gallons of wastewater per day. Commercial and industrial wastes include oils and grease, metals, and a variety of synthetic organic substances. In the Los Angeles area, about 85 percent of the flow to treatment plants is domestic sewage, and about 15 percent is industrial.
Municipal wastes are collected by an extensive network of main and feeder sewers that drain into central treatment plants where they undergo various levels of treatment, called primary, secondary and tertiary. Not all plants offer all types of treatment.
A primary by-product of the treatment process is sewage sludge (also referred to as biosolids). Sludge production increases significantly as plants upgrade to secondary treatment. Sludge can be a valuable resource (as it is often rich in nutrients) that can be combined with yard waste and made into commercial compost. The City of Los Angeles makes a commercial product called BioGro from collected yard waste and sewage sludge.
Sludge can also be a hazardous product if it contains high levels of contaminants such as metals and pathogens. Pollution prevention and source control programs that minimize these contaminants in wastewater therefore increase opportunities to effectively use this resource.
The region's municipal treatment plants provide service to over seven million people in portions of Los Angeles and Ventura counties. The City of Los Angeles' Hyperion Treatment Plant (Hyperion) and the County Sanitation Districts' Joint Water Pollution Control Plant (JWPCP) discharge treated wastewaters directly into Santa Monica Bay. The Las Virgenes Municipal Water District's Tapia Water Reclamation Facility periodically discharges tertiary treated wastewater into Malibu Creek.
Each day, about 645 million gallons of treated municipal wastewater are discharged to the Bay from Hyperion and the JWPCP. During exceptionally heavy rains, this volume increases due to infiltration of storm water runoff.
Hyperion Treatment Plant Discharges
Los Angeles' first ocean outfall was completed in 1894 and discharged raw (untreated) sewage across the beach near Playa del Rey. Today, the Hyperion Treatment Plant discharges a non-chlorinated mixture of primary and secondary effluent through an outfall located five miles offshore at a depth of 190 feet. Pursuant to a Consent Decree, the Hyperion Plant is undergoing a $1.1 billion upgrade to full secondary treatment levels, scheduled to be in place by 1998.
The City of Los Angeles' wastewater collection and treatment system serves over three million residents in a 480-square mile area. The Hyperion Plant is the largest of the City's four major wastewater treatment facilities and provides solids treatment for sludge discharged from two upstream facilities located in the San Fernando Valley. In 1991, Hyperion discharged 315 million gallons per day (mgd) of treated wastewater into the Bay, of which nearly 58 percent underwent secondary treatment and sludge digestion.
Joint Water Pollution Control Plant
Until the 1920s, most of the communities in Los Angeles County not serviced by Hyperion used cesspools and septic tanks. In the late 1920s, the County Sanitation Districts of Los Angeles County (CSDLAC) were formed and Whites Point on the Palos Verdes Peninsula was selected as an ocean outfall site, in part because it was far from the popular beaches of Santa Monica Bay.
The CSDLAC Joint Outfall System presently treats the wastewaters of more than four million people and 10,000 businesses and industries in a service area of approximately 583 square miles. Approximately 30 percent of the sewage in the Joint Outfall System is treated to tertiary standards in water reclamation plants and 70 percent is treated at the JWPCP in Carson. The JWPCP is the largest of the Districts' wastewater treatment facilities and processes solids from five upstream water reclamation plants.
In 1991, the JWPCP discharged an average of 330 million gallons of wastewater per day, 58 percent of which was subject to secondary treatment. (This flow is about 12 percent less than the average daily discharge of 356 million gallons during 1974 to 1987.) The combined flow is chlorinated and discharged through outfalls located approximately two miles off shore at a depth of 200 feet. The JWPCP residuals are sold as soil amendment or land spread or are disposed of in a landfill.
Like the Hyperion Plant, the quality of the JWPCP effluent has also improved. Since 1981, annual mass emissions of total suspended solids have declined by 62 percent and oil and grease by 48 percent. Significant reductions (ranging from 77 to 94 percent) in emissions of heavy metals have also occurred.
Until 1972, the JWPCP outfall discharged extremely high levels of the pesticide DDT, a result of the disposal of DDT process waste into the sewerage system. Following the termination of these inputs and the subsequent ban on its manufacture and use, DDT emissions have declined at a faster rate than originally thought possible. A comparable pattern is seen with emissions of PCBs, which have dropped to non-detectable levels since 1987.
Fifteen years after applying for a waiver from full secondary treatment, LACSD agreed in a lawsuit settlement to build a $400 million advanced treatment system. A full secondary treatment system is to be operational at the JWPCP by July 2002.
Tapia Water Reclamation Facility
The Tapia Water Reclamation Facility (Tapia) was constructed in 1965 as a joint venture agreement between the Las Virgenes Municipal Water District and the Triunfo County Sanitation District. The joint venture now also runs Rancho Las Virgenes, which grows feed crops for animals using dewatered sludge as fertilizer. Tapia serves a population of 80,000 from three cities, the western portion of Los Angeles County and a small portion of Ventura County.
The Tapia plant currently provides tertiary treatment of wastewater. Tertiary treated wastewater is reclaimed and used for irrigation, dust control and fire suppression. Sludge is currently digested and either pumped to land injection farms or dewatered and hauled to landfills.
Tapia has 10 million gallons per day of treatment capacity, although flows have averaged about 2.5 million gallons per day. The facility does not discharge on a daily basis, particularly in summer, since it can reuse much of the reclaimed water it produces. Annual mass emissions of total suspended solids, BOD, and certain metals have generally been low. Because flows in Malibu Creek are subject to human contact, Tapia's NPDES permit requires that discharged wastewater be completely pathogen-free.
More than 160 commercial and industrial facilities discharge into storm drain channels in the Santa Monica Bay watershed, and over 16,000 discharge into municipal sewer systems that flow to the Bay.
Industries that discharge into the storm drain system must provide on-site treatment and are subject to NPDES permit limitations; only non-process wastewaters can be discharged. Industrial storm water discharges to storm drain systems are also subject to NPDES permit limitations.
Facilities that rely on municipal systems are generally controlled under pretreatment or industrial waste discharge permits issued by the publicly-owned treatment works (POTWs) in accordance with federal, state and local source control regulations. Pretreatment processes remove toxic and conventional pollutants before they are discharged into sewage systems. Recent improvements in POTW effluent and sludge quality can largely be attributed to pretreatment and pollution prevention programs.
Industrial Dischargers to the Bay
Four major industrial facilities discharge treated wastewaters directly into the Bay. They include three electric power generating stations (the City of Los Angeles Department of Water and Power's Scattergood Plant, and Southern California Edison's El Segundo and Redondo Plants) and Chevron's El Segundo Refinery.
Power Generating Stations
The power generating stations use seawater from Santa Monica Bay to cool steam condensers. Cool seawater is pumped into the station, circulated through noncontact heat exchangers, and discharged at temperatures above the intake temperature. In addition to elevated temperatures, the once-through cooling water may include non-hazardous treated wastewater (as defined by state and federal regulations). Chlorine is also injected periodically to control biological growth.
El Segundo Refinery
The Chevron El Segundo Refinery has been in operation since 1911 and now manufactures various petroleum products including gasoline, jet fuel, kerosene, solvent, coke, fuel oil, liquefied petroleum gases and propylene polymer.
Since the early 1970s, Chevron has discharged secondary treated wastewater through an outfall 500 feet offshore of the beach at Grand Avenue. The refinery discharges six to seven millions of gallons per day (mgd) of treated water during dry weather and up to 20 mgd during wet conditions. In February 1993, Chevron announced that it would extend the outfall pipe to a distance of two-thirds of a mile, effectively removing the last industrial point source discharge from the nearshore environment.