After 20 years of polishing treated effluent from the Hickerson WRP, the existing traveling bridge sand filters had become increasingly difficult to maintain and repair due to lack of available replacement parts.

PSC developed a pilot protocol to evaluate four different cloth media filter technologies that could replace the outdated sand filters.  Once the protocol was developed, PSC performed pilot testing of the four technologies and evaluated them based on removal efficiency, backwash efficiency and the ability to handle upsets.  The pilot testing showed that two of the technologies tested could produce water with better quality than the existing system.  The effluent turbidity of the two technologies was roughly half of that produced by the existing filters  Site visits to full-scale implementations of the technologies were conducted along with EP Water operations in order to finalize the technology selection.

Once the preferred technology was selected, PSC developed a design to retrofit the cloth media technology into the existing filtration basins in the plant.  The resulting design will enable the plant to treat the full plant capacity in two basins while leaving one existing sand filter in place for emergency use.

The project also included the design of launder covers to be installed on the secondary clarifiers at the plant.  These covers will prevent algae growth on the launders and subsequent conveyance of algae to the filters.