Hypochlorite cost about twice as much as chlorine on an annualized basis and ozonation was even more expensive, but three UV systems were comparable to the cost of chlorination and dechlorination. An additional factor favoring UV treatment was an unused concrete denitrification channel in which lamps could be installed. It demonstrated that UV was just as effective as chlorination in killing bacteria and slightly more effective in destroying viruses found in the Martinez plant's wastewater. It also showed the lamps would need to be cleaned of fouling every two to four weeks. Montgomery Watson designed the UV system, which was installed in October 1996.
Water is piped to a treatment channel that is covered by a clear plastic lid to reduce algae growth.
Each bank holds approximately 400 lamps. Overhead cranes raise and lower the 9-ton banks to clean the lamps and replace those that are damaged or burned out. Cleaning is accomplished with dilute acids, such as 2-percent citric or phosphoric acid, in the lamp maintenance building. Both cleaning acid and replacement lamps are stored in this structure. The entire system consumes 700 kilowatts of power, translating to 70 to 80 watts per lamp.