Freese and Nichols was retained by the City of Fair Oaks Ranch to rehabilitate one final clarifier and correct a flow imbalance. The City of Fair Oaks Ranch operates a 0.25-MGD wastewater treatment plant. The plant has two secondary clarifiers. The clarifiers were built at two different times and the weirs are at different elevations. When the City operates both clarifiers in parallel, this difference in elevation creates a flow imbalance that operators must try to correct with manual manipulation of valves. In addition, the sludge collection mechanism was in need of major repair or replacement.
Freese and Nichols provided hydraulic analysis to identify means to correct the flow imbalance. Raising the clarifier walls in order to raise the weirs was the solution selected. Our team provided structural analysis to confirm that the walls could be safely raised.
The final project included raising the walls, installing a new center feed sludge collection mechanism, and modifications to the sludge and scum removal valves.