Water Treatment Facility Finished Water Storage Tank

The City of Mills was approved for grant funding to install a second finished water storage tank to build community resiliency, improve water quality, and protect public health.  The City of Mills' existing finished water storage tank is over 40 years old and needs to be rehabilitated as the interior tank coating is failing which is subjecting the tank to corrosion.  However, the existing tank cannot be taken out of service to be rehabilitated as there is no back-up finished water tank.  In addition to the corrosion, the existing tank has no check valve on the tank overflow. The lack of a check valve makes the tank more susceptible to intrusion by rodents which could result in significant water safety issues. This issue was noted in a sanitary survey of the City's water system conducted by the Environmental Protection Agency (EPA). A fully functioning finished water tank is critical to the City being able to provide water that meets drinking water standards. The finished water tank provides storage so the chlorine disinfection agents have sufficient time to work and maintain the required residual level. Residual chlorination is needed to reduce the chance of pathogen regrowth in water storage tanks or within the water distribution system. The City’s distribution systems are long distances from the finished water tank and there are a few dead-end sections. These areas are where water is not quickly used, and pathogens may re-grow if a proper chlorine residual cannot be maintained. The EPA has established standards for the chlorine residual that must be present at all points in the system and the finished water storage tank is critical in being able to maintain the required chlorine residual. The City of Mills needs a second finished water tank to allow for the rehabilitation of the first finished water tank and to improve community resiliency by adding redundancy to the water system.