USACE, Walla Walla District retained the Tetra Tech INCA, as part of a joint venture, to develop final designs and plans and specifications for the repair and refurbishment of clarifiers on the System 1 reuse treatment facilities and for the retrofitting of the existing fluidized bed sand filters at the Dworshak National Fish Hatchery near Orofino.

The plans modified five existing sand bioreacters to incorporate a continuous cleaning biofilter (CCBF) system using plastic bead media; modified the piping; and repaired the clarifiers and associated systems. The design included repair of the clarifier system in all eight of the clarifiers, cleaning of the clarifier ponds, replacement of the sludge pumps, and electrical connections and controls for the replaced equipment.