UOSA IFB 27-01 GAC Treatment Optimization

The Upper Occoquan Service Authority is seeking a contractor to retrofit and upgrade a granular activated carbon (GAC) treatment system for PFAS pilot testing. Phase 1 includes retrofitting one L/2 Building carbon contactor (two cells), restoring up‑ and down‑flow capabilities by modifying the underdrain nozzle system, and conducting a proof‑of‑concept evaluation for carbon transfer improvements. If Phase 1 is successful, a Phase 2 may follow to retrofit the remaining seven carbon contactors (fourteen cells) with the selected improvements. The work will be performed at the Authority’s treatment facility in Centreville, VA, and the contract documents provide full technical specifications. • Retrofit one carbon contactor (two‑cell unit) for PFAS pilot study. • Modify underdrain nozzle system to restore up‑ and down‑flow operations. • Conduct proof‑of‑concept testing and, optionally, extend to seven additional contactors in Phase 2.