Water. desalination + reuse

PROJECTS February-March 2014 | Desalination & Water Reuse | 25 | a significant role in the schedule for the construction of the offshore building and installation of the equipment in the building. The electrical installation also required a subsea cable to be run and secured along the ocean floor. Both SWRO facilities in the US Virgin Islands had existing structures in place. The existing intake structure at the Randolph E Harley Power Plant was onshore, but required restoration and a new electrical room. At the Estate Richmond site, the intake structure was in place and allowed for pump placement and installation only, along with associated electrical equipment. STEady-STaTE dESign vERSuS COmmiSSiOning nEEdS The facilities on St Thomas and St Croix were both sites that adopted a step-by- step commissioning strategy. Where it was not possible to fully commission a portion of the process, temporary systems were installed or interim bypasses created to continue on to the next system. The permanent design considered mostly steady state conditions. In these cases, there was a minimum amount of commissioning-only equipment. This is understandable when the extra expense and time required to implement these one-time-use designs is considered. The organization and efficiency of the project execution team resulted in a successful startup for both sites. By comparison, at the Point Fortin, Trinidad, site, operating equipment concurrent to commissioning equipment resulted in the plant being designed with pipelines, bypasses, and hydraulic feed systems for commissioning specific purposes. Incorporated in the design was each step of startup and how it would be accomplished. It allowed for expedited timelines without requiring a shutdown of running equipment in order to accomplish a commissioning objective. COnCluSiOn The technical differences between these three sites presented interesting challenges resulting in unique design characteristics. In consideration of the differences, each site was a success for the purpose of delivering fast, reliable and affordable water resources to each of these communities. The plant in Pt Fortin is the largest desalination plant built in Trinidad in 10 years and now supplies reliable, potable water to 29,000 residents, who had not previously had regular access to safe, clean drinking water. In the US Virgin Islands, in addition to making a social impact by improving the reliability of potable water supply to the territory, the cost savings incurred as a result of the transition from thermal desalination to state-of-the-art SWRO technology contributes greatly to the overall economic well-being of the territory.l Inside the Estate Richmond Power Plant SWRO facility on St Croix

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