The Potomac Water Filtration Plant has recently adopted a ferric chloride treatment process to provide more effective disinfection during the hot summer temperatures. However, the ferric chloride process will greatly accelerate the corrosion of steel and cast iron components submerged in the sedimentation basins.
Two technical studies completed between 2008 and 2010 identified submerged steel equipment to be replaced or coated with epoxy. While researching replacement equipment, EBA observed more extensive corrosion damage to the solids collection system’s auger and piping. With input from the equipment and coating manufacturers, EBA determined that the prior studies’ coating recommendations would not be effective.
Based on EBA’s recommendations and the subsequent failure of critical equipment, the project was expanded to replace the entire submerged solids collection system. While each basin was out of service, EBA inspected the concrete walls and floors to identify any needed surface and joint repairs.
EBA prepared the construction documents and construction cost estimate and provided engineering and inspection services during construction. EBA annotated the original construction drawings and shop drawings to show the replacement equipment. Where available, alternate materials were considered, such as stainless steel, ceramic, and polyethylene components.