GA Optimization for Las Vegas Valley Water Distribution System Operations and Water Quality

The Las Vegas Valley Water District (LVVWD) implemented an Energy and Water Quality Management System (EWQMS) using a daily hydraulic model during the summer of 2005. To date, the LVVWD has realized an apparent 11% savings in power cost and has improved water quality in its distribution system. To further enhance this effort, the LVVWD contracted with Optimatics to study applications of genetic algorithm (GA) optimization to its EWQMS. This study outlines how GA optimization can realistically be used for water distribution system operations and water quality, and illustrates the challenges that a GA developer and a utility have faced and resolved collaboratively. In order to be realistic and applicable to a utility system, the GA tool must be customized and the large number of decision variables such as pump on/off decisions must be addressed. Distributed computation has been implemented to significantly reduce optimization run time by utilizing a large number of the existing networked computers in parallel. The paper illustrates technical implementation and customization for the LVVWD including the necessary interface with its daily hydraulic model. A case study of minimizing water age for the LVVWD winter operation was investigated using a base model containing approximately 8,000 pipe sections, 194 pumps and 28 distribution system reservoirs. Preliminary results demonstrated that an approximately 13% reduction in average water age can be achieved by optimizing the 72-hour pumping strategy. Optimatics and LVVWD have continued the effort for extended operational and water quality applications using the GA tool. The paper includes the latest status of applications.