The McAlpine Creek Wastewater Management Facility (MCWWMF) is the largest wastewater treatment facility operated by Charlotte Water (CLTWater). In 2018, CLTWater began a Reliability and Process Improvements project. The project involved the rehabilitation of 16 secondary concrete clarifiers that ranged from 95 to 150 feet in diameter, with the oldest clarifiers being nearly 60 years old.
CLTWater considered an epoxy coating. However, they historically ran into issues with failures of delamination. Thus, they opted to move forward with a pilot study with four different epoxy manufacturers where they analyzed cost, schedule, performance, quality, service life, and safety. Concluding the test, CLTWater determined the single coat epoxy to provide the best value for their project.
The product selected was not the lowest cost option. Yet, the epoxy's single coat application and non-hazardous attributes provided CLTWater seven months of time savings resulting in the greatest cost savings as compared to the other products tested. The coating system achieved the high build needed in one coat to rehabilitate the concrete aggregate and allowed the clarifiers to return to service within four to six hours.
The product was also free of volatile organic compounds, solvents, styrene, and isocyanates, making the product safe for applicators, workers, and the surrounding work site. This allowed multiple trades to work concurrently while the coating was applied.
CLTWater is one of the largest water entities in the Southeast region, managing a total of ten water and wastewater treatment plants serving a population of approximately one million. The MCWWMF is the largest wastewater treatment plant of five wastewater facilities owned and operated by CLTWater, rated at a 64 MGD treatment capacity and accounting for over half of CLTWater's wastewater treatment system.
The MCWWMF Reliability and Process Improvements Progressive Design-Build was a $138 million project issued in March 2018 to address aging infrastructure concerns as the original plant was built in the 1960s. The improvements scope of work included the rehabilitation and replacement of critical primary and secondary wastewater treatment structures over five years. The owner awarded the design builder this scope, including the rehabilitation of 16 secondary clarifiers, 28 aeration basins, and replacement of the plant’s three blower buildings, all while maintaining plant operations. In addition, the project included the installation and operation of a Return Activated Sludge (RAS) Fermentation Pilot Study, with data evaluation and implementation of a full-scale RAS fermentation system.
