Hydraulic Models Shed Light on Water Age


  • Jeffrey Cruickshank, Hazen and Sawyer

Instead of focusing on the quality of water leaving treatment plants, regulations are now concentrating on the quality of water delivered to customers. That’s causing utilities to take a closer look at distribution system water age.

Water age is on the radar screen of many utilities because excessive age can cause problems of disinfection by-products (DBPs). This is a hot topic because a US Environmental Protection Agency (USEPA) regulation—the Stage 2 Disinfectants and Disinfection Byproducts Rule—requires utilities to conduct initial distribution system evaluations (IDSEs) to select new DBP sampling sites. DBP compliance monitoring begins in 2012 or 2013, depending on the population served.

Many utilities have chosen to conduct IDSEs using hydraulic models instead of extensive monitoring programs. Models are beneficial because—in addition to calculating water age for existing conditions— they can predict what will happen if operating procedures change. It’s easier to test ideas in a model than to subject an entire distribution system to trial-and error testing…

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Horizons showcases significant water, wastewater, reuse, and stormwater projects and innovations that help our clients to achieve their goals, and can help you achieve yours. Articles are written by top engineers and process group leaders, demonstrating and explaining the beneficial application of a variety of technologies and tools.

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