Southern Nevada Water Authority Stage II Reliability Upgrades Project: Transient Analysis of 341 ML/d (90 MGD) Monthill Pumping Station and 681 ML/d (180 MGD) Hacienda Pumping Station

A transient analysis was completed for the 341 megaliters per day (ML/d) (90 MGD) Monthill Pumping Station (PS) that will provide redundancy for the 681 ML/d (180 MGD) Hacienda PS—a critical facility serving the central area of Las Vegas. A comprehensive transient analysis was carried out to identify and mitigate potentially damaging water hammer conditions with the Monthill and Hacienda PS’s operating alone, as well as concurrently. This paper will review the use of direct-on-line starters versus soft-starters; using non-slam check valves in conjunction with pump control valves; results with a throttled air chamber; and methodology used to recommend pump control valve opening and closing times.