Transient Flow Modeling and Verification of a 20-MGD Raw Water Conveyance System
Transient flow conditions in a closed pipe system refer to the change in steady-state conditions that occur as a result of planned or unexpected operational changes. These changes typically result in undesirable pressure fluctuations in the pipe that could result in catastrophic failure or increased operation and maintenance costs unless the system is adequately designed to handle these phenomena. The analysis of transient flow conditions is somewhat complex and requires specialized understanding of the system behavior. With the advancement in the computer speed and software technology, user friendly transient flow analysis software is now available to model the transient behavior in pipe network and establish design parameters to adequately protect the system.
This chapter presents the hydraulic and transient modeling of the Skiatook Raw Water Conveyance System (SRWCS), surge model calibration using field data, and post improvement verification of the computed performance. Surge 2000© software was used in the analysis. In addition, this chapter also discusses how hydraulic modeling was effectively used in establishing additional raw water storage that results in considerable savings in pumping energy cost.
The SRWCS is jointly owned by the cities of Sapulpa and Sand Springs to convey raw water from Lake Skiatook to their respective treatment facilities. The cities of Sapulpa and Sand Springs are located just west of Tulsa, Oklahoma, and the Lake Skiatook is located northwest of Tulsa. This system was originally completed in 1992 and included a strainer building, a pump station and approximately 24 miles of 36- and 24-inch raw water transmission lines and storage. The original pump station included four vertical turbine pumps 75 hp, 200 hp, 400 hp and 600 hp, respectively. To meet increased demand, the pump station was upgraded in 2002 that included replacement of the smallest pump with a new 1250-hp, 15 million gallons per day (mgd) pump and improvements to the strainer and surge control systems. The transient analysis was performed as part of this upgrade.
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