2662 East Walnut Street
Ontario, California 91761
Regional Water Recycling Plant No.1 (RP-1) is located in the city of Ontario and has been in operation since 1948. The plant has undergone several expansions to increase the design hydraulic domestic sewage (wastewater) treatment capacity to 44 million gallons per day. The plant serves areas of Chino, Fontana, Montclair, Ontario, Rancho Cucamonga, Upland, and solids removed from RP-4, located in Rancho Cucamonga. The plant treats an average influent wastewater flow of approximately 28 million gallons per day. The plant is broken into two separate treatment sections: liquids and solids.
The liquid treatment section consists of preliminary screening and grit removal, primary clarification, secondary treatment by aeration basins and clarification, tertiary treatment by filtration and disinfection, and dechlorination. Wastewater liquid is treated to State Division of Drinking Water Title 22 Code of Regulations standards for disinfected tertiary recycled water. The solids treatment section begins with thickening the solids removed from the primary and secondary clarification processes. The thickened solids are pumped to anaerobic digestion and then to the centrifuges for dewatering. Wastewater solids are digested to a minimum Class B biosolids standard, as defined by the United States Environmental Protection Agency Code of Federal Regulations. After dewatering, the biosolids are hauled to the Inland Empire Regional Composting Facility in the city of Rancho Cucamonga for further treatment to produce Class A compost.