P Street WWTP Phase I Wet Weather Improvements

Project Description

The City of Fort Smith, Arkansas, in seeking to eliminate wet weather sanitary sewer overflows in the wastewater collection and transmission system, expanded the P Street Wastewater Treatment Plant from a Peak Flow Capacity of 24 million gallons per day (MGD) to 55 MGD. This expansion included the addition of one 100-foot diameter conventional secondary clarifier for a 9 MGD expansion of the plant’s biological treatment process. The project also included the addition of a chemical-physical treatment process or high rate clarifier to treat a Peak Wet Weather Flow rate of 22 MGD. Since the chemical-physical treatment process did not meet the regulatory definition for biological treatment, all of the effluent from this treatment train is stored in a 20-million gallon earthen equalization basin that was constructed as part of the Project. The construction of an Effluent Pump Station was also included in the Phase I Wet Weather Improvements. The Effluent Pump Station allowed the P Street Wastewater Treatment Plant to pump the full biological capacity of the P Street Wastewater Treatment Plant to the Arkansas River when river levels become too high for a normal gravity discharge. The total cost of the Phase I Wet Weather Improvements was approximately $16 million. The Design Team included Hawkins-Weir Engineers in association with CDM Smith with Hawkins-Weir providing the lead role in the construction management efforts for the project.