Pima County Regional Wastewater Reclamation District (RWRD)
Construction Manager at Risk (CMAR, CM/GC)
MWH was the CMAR for this plant expansion centered on a 50 million gallons a day (MGD) liquids and solids train replacement. The project also included the construction of a new 37.5mgd, five-stage Bardenpho treatment process by upgrading three 12.5 MGD 3-stage Bardenpho processes and constructing a new 12.5 MGD basin. This project also involved two digesters, a blower building, a primary clarifier, two new aeration tanks, five new secondary clarifiers, three new centrifuges, and a new gravity belt thickener building.
MWH managed preconstruction, GMP development, and general contracting services during construction. In addition, MWH self-performed over 43% of complex aspects of the work to control the critical path, including procurement, installation of process mechanical piping and equipment, six miles of yard piping, instrumentation and control, and commissioning and startup.
MWH created 4D BIM to verify site logistics, yard operations, and temporary facilities. By reviewing the schedule in a rich, visual format, our team made sound decisions based on multiple sources of accurate real-time information. As the design changed, the model automatically identified the changes and their respective impact on the project’s critical path and overall delivery. MWH used 5D BIM to monitor the project’s construction cost throughout the design, rapidly generating an array of essential estimating information, including materials quantities and costs, size and area estimates, and productivity projections.
To ensure the existing functionality of the plant remained fully operational as required, MWH developed over 450 MOPOs to complete 250 mechanical tie-ins, 350 electrical switchover ties, and three plant shutdowns without incident. The entire project, including construction commissioning and startup, was completed while maintaining a fully operational plant.