The Sand Island Wastewater Treatment Plant (SIWWTP) is Hawaii’s most extensive treatment plant, servicing the metro and greater Honolulu area. Hawaiian Dredging designed and constructed a new ultraviolet (UV) disinfection system, including a new control system to handle all existing and future UV disinfection processes. The new UV system will increase disinfection capacity by an additional 30 million gallons per day, provide system reliability, reduce energy consumption, and lower operating costs.