AWWA WQTC71388

Softening and coagulation practices at the Bay City Municipal Water Treatment Plant (BCMWTP) in Bay City, Michigan, profoundly impact both pipe-scale stability and corrosion control treatment effectiveness, as well as many other water quality compliance issues. Rapid variations in raw water hardness, particulates and natural organics make it difficult for Bay City to meet finished water quality goals necessary for optimum corrosion control treatment, resulting in isolated increases in tap water lead levels and red water complaints during 2007 and 2008. A desktop evaluation was completed to assist Bay City in developing alternatives to re-establish optimum corrosion control treatment practices while maintaining compliance with other critical regulatory requirements and water quality goals such as disinfection byproducts (DPBs) and hardness. Optimization of Bay City's corrosion control treatment requires a careful balance between challenging and sometimes conflicting water quality goals for lead and copper solubility, coagulation and softening, scale stability/aesthetics, taste and odor, disinfection, DBPs, residuals handling and other issues. Includes extended abstract only.