Dec 16, 2010

Salt Lake City Implements Bentley Analysis Software for Its Water System

WaterGEMS and Hammer software integrated with city's existing GIS

Bentley Systems Inc. announced that Salt Lake City selected and deployed Bentley´s WaterGEMS V8i modeling and analysis software and Hammer V8i transient analysis software to analyze, design and operate its water distribution system. The system serves approximately 450,000 residents and includes about 1,380 miles of pipes.

Salt Lake City has a complete geographical information system (GIS) for its water, sewer and storm water infrastructure, for which each pipe in the various systems has been surveyed. The city´s goal was to create a hydraulic model of its water distribution system using its existing GIS so that it could maintain a one-to-one relationship between the two.
Bentley´s WaterGEMS and Hammer products enabled the city to accomplish this and helped make the model building and updating processes more efficient.

"Our first priority when selecting our water modeling software was to make sure the water model could be integrated with our GIS and maintained or updated easily. The city chose Bentley´s WaterGEMS and Hammer due to the software´s ease of use and full interoperability with Esri´s ArcGIS," said Brandon Arnold, GIS specialist at the Salt Lake City Department of Public Utilities.

The new water model was built from scratch using WaterGEMS and the city´s GIS. Once the pipe layout and connectivity were established, the software´s LoadBuilder and TRex tools, which are common to both applications, were used, respectively, to allocate water demand and elevations to the hydraulic model´s nodes. Pressure reducing valve (PRV) settings were imported from the GIS, and pump curves and controls were added.

"WaterGEMS´ Network Navigator and Pressure Zone Manager were extremely helpful in picking out the small system details and locating the few errors that existed. With 55 zones modeled, which include more than 38,000 pipes, the Salt Lake City water system can be a little overwhelming at times. The Pressure Zone Manager was great for zone-by-zone analysis, and it also made model building much more efficient,” said Arnold. “Tracking down a missing closed valve sometimes can be tricky.With the Pressure Zone Manager, it is easy to tell where the zones are connected. Once the zones have been established, the data that the WaterGEMS model calculates and displays, including the boundary nodes and total flow into and out of the zones, is very helpful. Overall, the model building process was relatively simple."

The city’s hydraulic analyses now can include fire flow analysis, pipe sizing for new design projects and some master planning. Many of the city´s ongoing projects rely on the WaterGEMS model. Future projects will be challenging, since model assumptions evolve as population grows, the distribution system expands, and the pipe infrastructure ages. For these reasons, both the GIS and water model need to be kept up to date.

"Keeping the GIS and hydraulic model synchronized is one of the biggest challenges, as we certainly want to avoid having to rebuild the water model from scratch every time the GIS is updated,” said Arnold. “The GIS-ID feature in WaterGEMS will be a big help in maintaining that relationship between the model and our up-to-date GIS. It is particularly handy to be able to split a pipe or add a valve in the model without altering the relationship to the GIS. It makes updating the model a cleaner and easier process."