The 34 MGD Otay Water Treatment Plant in San Diego, California serves a population of approximately 200,000. It is a conventional treatment plant that uses coagulation, flocculation, sedimentation, filtration and disinfection. The plant receives raw water from two different sources — imported water from the Colorado River and runoff water from three local reservoirs.
With the introduction of EPA’s Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR), regulations became more stringent for Trihalomethanes (THM) and Haloacetic Acids (HAA). As a result, the current method of chlorine disinfection was no longer an effective solution and the plant decided to pursue a new DBP control strategy.