PCL Construction, in collaboration with joint-venture partner Sundt, is under construction on the North Water Treatment Plant located in Gilbert, Arizona. The new facility will replace the plant's current capacity of 45 million gallons per day (MGD) to 60 MGD at full capacity to serve Gilbert and the surrounding communities. To successfully complete the project while maintaining facility operation, the project has been divided into five phases, each contributing to the overall improvement and modernization of the facility.
The initial phase focused on constructing a new solids handling facility, as new buildings for the plant would be built in the footprint of the existing solar drying beds. In phase two, the project team prioritized the procurement of long-lead materials including under-slab piping for the new Filter Complex and the construction of a new raw inlet structure connected to the Salt River Project (SRP) canal system. The construction of the inlet structure became a time-sensitive and fast-paced project that needed to be completed during a rare, once-in-a-decade shutdown of SRP operations. The project team efficiently organized and coordinated their efforts to meet the schedule requirements by using a temporary cofferdam that would allow construction of the inlet structure while the canal was in operation.
Phase three of the project, which began in June 2023, includes the construction of a new filter complex, chemical facility, operations center, pump station and the installation of various electrical components necessary to power the facility. Due to demand and previous supply issues caused by the pandemic, medium-voltage electrical gear was identified early on as a high-risk schedule item. To overcome potential delays, the team proactively identified long-lead items and developed a plan to coordinate the early release of critical electrical equipment. Leveraging support from regional PCL offices and industry relationships, the team worked closely with equipment suppliers to secure early-release electrical equipment bid packages and maintain the project’s critical path.
The fourth phase of the project, which began in December 2023, includes the construction of a new granular activated carbon (GAC) facility, sodium hypochlorite generation facility, pump stations and the wash water recovery basin. While not immediately necessary for start-up, the inclusion of a granular activated carbon system aims to enhance water quality and manage disinfection by-products created by the interaction of naturally occurring organic material with chlorine.
The final phase of the project is currently under design but will include the construction of two new pre-sedimentation basins, a sludge pump station and demolition and re-purposing of portions of the existing treatment plant and supporting facilities once the new plant is completely commissioned.
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