Water that flows from kitchens and bathrooms inside local homes and businesses can contain harmful organisms and substances that present potential health and environmental hazards. Our job is to collect that wastewater, draw it safely away from your property and transport it for processing that eliminates these potential hazards.

The District owns and operates the wastewater treatment plant that serves Fairfield, Suisun City and Travis Air Force Base. Water that drains from kitchens and bathrooms inside local homes and businesses flows to the wastewater treatment plant, where it is cleansed through various biological and chemical steps.

The wastewater collection system is designed somewhat like a tree. The smallest-diameter branch sewers in city streets are connected to individual homes and small businesses. Several branch lines connect to main sewers that serve entire neighborhoods or business districts. They, in turn, feed into larger diameter trunk lines that lead into our treatment facility.

Wastewater undergoes a multi-step treatment process at our central facility. First, the wastewater passes through a screening process that traps large solid objects that may have accidentally entered the system. Grit chambers then remove sand and sediment from the flow, and primary sedimentation tanks allow heavier food-related wastes to settle from the water. Next, an intermediate treatment step uses bacteria growing on large honeycomb-like plastic blocks in towers to remove a significant proportion of remaining organic matter. The next step, called “activated sludge treatment,” takes place in concrete tanks bubbling with air, where more microorganisms consume any remaining organic matter.

Following aeration, the water is transferred to a secondary sedimentation pond for removal of the microorganisms. Any particles remaining are extracted as the water runs through a network of tertiary sand filters. In a separate basin, chlorine disinfects the filtered wastewater by killing pathogenic organisms. Finally, chlorine is removed and the water is ready to be released to the environment, or recycled for irrigation. The District takes pride in refining its processes when developing technologies allow for significant improvements, and is currently working on converting its chlorine gas disinfection system to an ultraviolet (UV) disinfection system. UV light, when used for wastewater disinfection, produces no known by-products and does not pose the chemical safety and security concerns of chlorine gas.

Solids removed during the various processes are thickened and treated through a process called “digestion” in a closed vessel. Methane gas produced as a natural byproduct of the digestion process is used to fuel electrical generators that the District owns, thereby reducing reliance on PG&E for electrical energy. A “dewatering” process further dries the solids, preparatory to proper disposal.

The fully treated water leaving the treatment plant is nearly as clean as drinking water. The plant’s complex pollutant-removing treatment processes protect the health and environment of local citizens and the Suisun Marsh.

Stormwater collection is handled through a system that is completely separate from the wastewater system that captures and transports sewage. All of the stormwater that our network of storm drains and pipes collects flows untreated into the Suisun Marsh, an environmentally-sensitive area of enormous proportions.

The Environmental Services Office of the California Department of Water Resources has identified Suisun Marsh as the largest contiguous brackish water marsh remaining on the west coast of North America. This critical component of the San Francisco Bay Delta estuary ecosystem is a staggeringly expansive region of 116,000 acres, encompassing 52,000 acres of managed wetlands, 27,700 acres of upland grasses, 6,300 acres of tidal wetlands and 30,000 acres of bays and sloughs. More than 10 percent of the remaining natural wetlands in California are within the Suisun Marsh.

The marsh contains habitat for more than 220 bird species, 45 animal species, 16 different reptilian and amphibian species, and more than 40 fish species. The Department of Water Resources has further determined that 80 percent of the state's commercial salmon fishery benefits from the marsh’s tidal rearing areas, where juvenile fish grow twice as fast as those reared in the upper watershed, thereby enhancing their survival. The marsh also serves as the resting and feeding ground for thousands of waterfowl traversing the Pacific Flyway.

And yes, the Suisun Marsh does play a role in the drinking water supply as well. The 230-miles of winding levees within the marsh help to protect the drinking water supplies for 22 million people by preventing salt water intrusion into the Sacramento-San Joaquin Delta. To maintain this pristine environment, the District assists the cities of Fairfield and Suisun City by participating in the URMP (Urban Runoff Management Program), and by maintaining the cities’ stormwater pumpstations.

The URMP is intended to reduce or eliminate pollutants discharged from the urban environment into our storm drains, local creeks and the Suisun Marsh. Water flowing into our gutters and storm drains is not treated before discharge into our creeks, which feed into the expansive Suisun Marsh. Key components of the URMP include industrial and commercial inspections, education outreach to schools and the general public, monitoring municipal maintenance activities, and ensuring that local residential and commercial construction sites do not contribute to pollution in our local waterways.

All of us at the Fairfield-Suisun Sewer District take our responsibility to protect the Suisun Marsh and our region’s other vital environmental attributes very seriously. We hope you do as well. Together, we can protect and preserve these essential natural resources for generations to come.