Filter Multimedia and Underdrain Nozzle Replacement Project

The Central Coast Water Authority (CCWA) is a joint powers agency formed to construct, own, and operate certain facilities needed to treat, convey, and deliver State Water Project (SWP) water to its project participants retail water providers and end users located within the County. The Polonia Pass Water Treatment Plant (WTP) is one of CCWA's facilities and stores treatment chemicals in chemical tanks. The condition of the multimedia filters at the WTP is a high priority due to their critical role in the treatment process and regulatory compliance. Proper filter performance is essential to prevent clogging, excessive head loss, and inefficient backwash cycles, all of which can adversely affect WTP operations. Filtration of settled water is a core component of overall treatment capacity and is achieved through eight multimedia filters, within the system. Water percolates from the top of each filter through a layer of granular activated carbon and sand and flows through an underdrain system to the chlorine contact basin. CCWA intends to remove and replace both layers of filter media and the underdrain nozzles in four of the filters, repairing filter basin concrete surfaces, and leveling backwash troughs to extent feasible.