This expansion to the Patuxent WFP provided an entire new main treatment train along with extensive modifications to the existing plant. Treatment processes on the additional train included flocculation, sedimentation, UV disinfection, and filtration. A powdered activated carbon (PAC) storage silo and feed system were added, as well as a new potassium permanganate vacuum system. Additional upgrades included the construction of two new gravity thickeners, a sludge pump station, centrifuge dewatering equipment, sludge truck loading equipment, and truck scales. Chlorination systems for the existing treatment trains were replaced with UV disinfection facilities.
The project required the replacement of two 2,400V switches, two 2,400V/480V transformers, and one Main-Tie-Main 480V switchgear. The initial construction sequence planned for multiple partial plant shutdowns, including prolonged exposure to “single-feed” conditions. Through coordination with WSSC and the design engineer, Ulliman Schutte implemented an alternate plan that effectively isolated the portions of the existing equipment, allowing it to be replaced in its entirety rather than in multiple sections. This alternate approach allowed the plant to maintain full capacity and reduced the risks associated with extended single-feed operation.
