Wastewater Collection and Hill Canyon Wastewater Treatment Plant A Brief History As recently as the late 1950s, a centralized wastewater treatment facility did not exist in the Conejo Valley. Yet, the need for such a facility was acute, as the use of septic tanks, the most common method of waste disposal, was unable to meet the needs of the rapidly growing community. Because of this, the Conejo Valley Sanitary Company, a subsidiary of the Janss Corporation, constructed a small treatment plant in 1961. The City of Thousand Oaks was incorporated in 1964. With new housing and business developments, waste disposal continued to be a major problem. So much so, that in 1965, the City Council resolved that the "proper disposal of sewage is the most urgent problem facing the Conejo Valley," and called for the establishment of a "municipal sanitation system at the earliest possible time." That time came on July 1, 1966 when, backed by a voter-approved bond issue, the City purchased the Conejo Valley Sanitary Company and with it, the Hill Canyon Wastewater Treatment Plant. This facility provides treatment for wastewater from about 90 percent of the City. Wastewater generated in the Westlake portion of the City is collected and treated by the Triunfo Sanitation District. Both treatment plants operate under National Pollutant Discharge Elimination System permits. The Wastewater Division The City's Public Works Department, Wastewater Division, is responsible for the planning, administration, operation, and maintenance of the wastewater collection and interceptor systems, as well as the Hill Canyon Wastewater Treatment Plant. Structured as an enterprise function of the City, revenues for the Division's activities are funded by existing and new system users through service and connection charges. City wastewater facilities currently treat an average of 11.0 million gallons of wastewater per day generated from its domestic, commercial, and industrial customers. The water is treated to a level that complies with a wide variety of operational permits and creates a final product that can be beneficially reused. This effort is unrelenting, and the positive environmental results can be viewed all along the Calleguas Creek. Reclaimed Water In order to best utilize this valuable resource, the City, in conjunction with other governmental entities, has developed the Calleguas Creek Diversion Project. This project is the result of a long water rights process that has recently been completed with the approval, by the State Water Resources Control Board, of the City's appropriative water permit. Now operational, the project diverts reclaimed water discharged from the Hill Canyon Wastewater Treatment Plant for agricultural reuse on farmlands in the Santa Rosa Valley and the Oxnard Plain. This project will have substantial regional benefits in that it will allow downstream water users to reduce groundwater pumping. This will also help reduce groundwater overdraft problems and prevent sea water intrusion in the Oxnard Plain. Wastewater Treatment Plant Update On average, 11.0 million gallons of water are treated and recycled into the environment through the City's wastewater treatment plant. Wastewater is treated to a tertiary level. By the time it is discharged to the creek, following a process of screening, grit removal, clarification, nutrient removal, secondary clarification, multi-media filtering, disinfection, and dechlorination, its crystal clear appearance is very similar to that of high quality potable water. Biosolids Biosolids, the solids that are removed from the water and anaerobically digested and dewatered, are trucked to Kern County where they are composted to an Environmental Protection Agency "Class A, Exceptional Quality" level final product which is available for recycling as a soil amendment. Recycling of this soil amendment on marginal agricultural lands has beneficially increased crop yields of cotton, alfalfa, and other non-edible crops. Biosolids recycling is regulated by the Environmental Protection Agency as well as by local ordinances. Wetlands Mitigation Bank In 2003, a five-acre wetlands project was constructed at the Hill Canyon Wastewater Treatment Plant as part of Phase 3 construction activities. These engineered wetlands are fed from a diversion structure downstream of the treatment plant's effluent discharge. Approximately one million gallons a day of reclaimed water flow through the wetlands creating a stunning habitat for birds, fish, animals, and reptiles. The City will use the wetlands project as a mitigation bank to offset environmental effects of other City projects. Summary The City of Thousand Oaks wastewater collection system and the Hill Canyon Wastewater Treatment Plant have an excellent operational environmental record. Ongoing construction to improve the collection system and treatment plant capacity and reliability will minimize the possibility of system overflows or permit excursions, decrease liability exposure, and simultaneously improve effluent and environmental quality. Meeting new and more stringent environmental standards and regulations, whether in the wastewater collection system or at the treatment plant, is a never-ending challenge and the ongoing mission of our professional wastewater system staff. Meeting this challenge means recycling our imported water to be beneficially reused for agriculture on the Oxnard Plain, the preservation of riparian habitat from the City’s treatment plant to the Mugu Lagoon, and the beneficial recycling of biosolids for soil improvement in the Central Valley. It is a monumental environmental effort, and it happens every day. For comments or suggestions, email cerogers@toaks.org.