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In an ongoing effort to further improve its activated sludge treatment process, the Searcy Wastewater Treatment Plant recently replaced its aging equipment and improved its process flow train. Two of these improvements involved the design and construction of peripheral feed secondary clarifiers to succeed the rectangular clarifiers and the replacement of the aging influent pump station.
Garver designed and provided construction administration for two new peripheral feed secondary circular clarifiers, 115 feet in diameter with a 15-foot water depth, to replace the rectangular clarifiers. Constructed by Robinson Mechanical Contractors Inc. of Perryville, Mo., the project also included the construction of a new return activated sludge/waste activated sludge pump station, flow divider box, mixing box for the RAS, various yard piping, and abandonment of existing structures.
The second improvement involved replacing equipment at the out-of-date and small influent pump station. Garver analyzed the existing pump station and wet pit/dry pit structure and concluded it would be more feasible to design and construct a new station rather than rehabilitate the facility. Plans were designed to construct a concrete pump station with submersible pumps, a concrete valve vault, and an electrical building adjacent to the pump station. The new station has three pumps that work in a triplex scenario to direct flow to the wastewater treatment plant and two pumps to direct flow to the stormwater holding pond.
Variable frequency drives were installed on the pumps allowing a more constant flow to the plant, which in turn keeps the activated sludge process from seeing large swings in influent flow. Additionally, automated valves were incorporated in the pump station to allow the water from the holding pond to be gravity fed back to the pump station during lower flow periods. |
