GeoWorld August 2012

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T he Las Vegas Valley Water District (LVVWD) designed a custom Valve Isolation (VI) system that helps measure the impacts of service out- ages as well as quickly identify strategies to isolate water-main breaks. Although integrated within the district's GIS, VI is designed for non-GIS users, specifi- cally those responsible for the daily operation of the water-delivery system. This approach reaped significant benefits: operational staff used VI to help develop outage plans for key areas, prioritize preventative maintenance tasks and identify valves critical in isolating potentially large main breaks. The Asset Management department is using the system to prioritize rehabilitation projects based on "down- stream" system impacts, and field staff use VI to report errors to the GIS staff for corrections. VI Stops the Drip VI is a process by which water-network impacts can be assessed by a GIS based on a main-break location. The GIS also can identify which valves to operate to isolate the leak. Such powerful analysis can be used to quickly enumerate service outages, target critical valves in a major shutdown scenario and identify potential weak- nesses within the water-distribution system (e.g., lack of redundant flow in cases of valve failure). Most commercial GISs have VI capabilities, but com- mercially available VI analysis depends on an accurate network model optimized for specific GIS software. In addition, the mechanism for "executing" VI can be dif- ficult or awkward depending on the software used and the specific problem to be solved. This often relegates the use of VI analysis to GIS professionals. The LVVWD AM/FM/GIS Division has long used net- Figure 1. The LVVWD VI system uses a custom algorithm, Java servlet engine and Web interface to return results to users. The Las Vegas Water District Manages Service Outages Before they Happen work tracing and VI functions to test the integrity of its GIS and evaluate impacts from main breaks. However, issues arose when investigating this technology for daily operational use. These included the suitability of the GIS data (referred to as a geometric network) for accurate network tracing and a lack of key functionality available within the GIS. Figure 2. A VI module walks users through an analysis. Results include affected services and valves that isolate the break. AUGUST 2O12 / WWW . GEOPLA CE . COM 23

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