Optimizing Operations and Protecting the Distribution System with Transient Modeling

Authors:

  • Crystal Broadbent, Michael Wang - Hazen and Sawyer
  • Kelvin Creech - Town of Cary

This presentation will show how a transient model can be used to identify problems affecting finished water pump operations at a water treatment plant. The finished water pumps influence the hydraulics of the entire distribution system. Therefore analyzing the complete system can assure the most cost efficient solution. This case study will show how the Town of Cary, North Carolina, used a calibrated surge model to improve pump operations and transmission mains.

The Town’s water treatment plant, rated for 40 mgd, has nine finished water pumps. After the 42-inch transmission main had been drained for maintenance, the Town’s staff was unable to purge all the air out of it when the main was returned to service. They also noticed high-pitched sounds emanating from the existing air release valves during the refilling process. The staff suspected that the finished water pumps were adversely affected by the entrained air left in the transmission main.

A surge model was developed from the Town’s current hydraulic mode. The surge model was calibrated using both SCADA records and field measurements. Field test use equipment that was able to capture pressures more frequently than SCADA data. These measurements captured the pressure transient along the transmission main during normal pump shut-down and start-up.

The surge model was then used to analyze the existing problem and design properly-sized and optimally-located air release valves. The new air valves will allow town staff to quickly return the 42-inch transmission main to service. The air valves also allowed the finished water pumps to operate more efficiently, providing a cost savings to the Town. The project also included evaluation of a surge protection vessel which would help protect infrastructure and maintain drinking water quality.

The recommended improvements will be described in detail so that audience can learn how a calibrated transient model can help optimize operations, reduce O&M costs, and protect critical infrastructure. Treatment plant and distribution system operators will benefit from this presentation as will water utility managers interested in these potential benefits to their distribution systems.

For more information, please contact the author at cbroadbent@hazenandsawyer.com.

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Horizons Fall 2017 (pdf)

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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