Yadkin Regional Water Supply Project — Water Treatment Plant Design Development for Union County's Future Needs

Union County and the Town of Norwood, NC, are working to ensure a long-term, sustainable water supply for current and future residents in the Yadkin River Basin. The infrastructure of the Yadkin Regional Water Supply project includes a new water intake and pump station on Lake Tillery in Norwood; a raw water supply pipeline to convey the supply to a new greenfield water treatment plant (WTP) in Union County; and a new finished water pipeline to convey treated drinking water to the residents of Union County. Union County selected the design-build delivery method to implement the WTP and finished water pipeline components of the project, working in collaboration with Union County Engineering and Operations staff, CDM Smith, and Program Manager, HDR. The County recognized the unique demands of the Yadkin Regional Water Supply Project and determined early in the project process that an integrated project delivery method would yield distinct advantages over a traditional design-bid-build approach. With the support of the County's selected program manager, multiple delivery methods were evaluated including Construction Manager at Risk (CMAR), fixed price design-build, and progressive design-build. Progressive design-build was selected as the project delivery method as it offered the greatest flexibility and least risk to the County to implement this $260M+ program of improvements to delivery sustainable water to the residents of Union County. The design-build project delivery approach has yielded the desired outcomes for the County. Design-build teams were selected based on qualifications, laying the foundation for success by engaging partners with extensive experience in the industry and project delivery method. The project has also realized an accelerated delivery schedule, cost certainty, and an innovative, collaborative, and value driven approach to the design. This presentation will focus on the design development of the 12-mgd WTP and approximately 10 miles of finished water pipeline. Initial design activities included a comprehensive review of treatment approaches for the Lake Tillery raw water supply and selection of a conventional treatment process, including rapid mixing, flocculation, and high-rate clarification with plate settlers followed by dual-media filtration including granular activated carbon over sand. The site layout and hydraulic profile were developed with provisions for advanced treatment if required due to water quality or regulatory changes in the future. Detailed design development commenced after the treatment technology was selected and was completed utilizing integrated, coordinated Building Information Modeling (BIM). The WTP design also includes raw and finished water storage, supporting chemical storage and feed systems, and reclamation basins for residuals management. The finished water pipeline consists of just over 10 miles of 36-inch diameter pipe that traverses predominately rural areas and includes seven trenchless crossings of NCDOT roadways and an open-trench crossing of the headwaters of Lake Twitty. The presentation will highlight the design development, the process of developing and finalizing the Guaranteed Maximum Price (GMP) for the WTP and finished water pipeline, and also highlight early activities associated with construction of the project, which commenced in January 2021. Commissioning and system activation is planned for Summer 2023.