Somerton Wastewater Treatment Plant Expansion

Kiewit was selected by the City of Somerton for the expansion of their Sequential Batch Reactor (SBR) Wastewater Treatment Plant (WWTP). Prior to the design commencing, Kiewit performed cost modeling and constructability reviews to aid in the determination if a Biological Nutrient Removal Process (BNR) design would be more beneficial than the original concept. Kiewit provided anticipated construction costs and schedules for the conversion of the existing SBRs to a BNR. Kiewit performed the same analysis in developing the cost and schedule for the construction of additional SBRs. These side by side comparisons allowed the selection of the best value expansion approach for the WWTP. The BNR approach was selected and increased the current .8 MGD to 1.8 MGD for an addition of .6 MGD in capacity from the original concept.

The expansion consisted of construction of two new 60’ diameter WesTech secondary clarifiers with RAS/WAS pump station. A masonry dewatering building addition was constructed complete with two Huber screw press units, an Enpro polymer feed system and Grundfos booster pumps for solids handling to replace the removal of the existing sludge drying beds. Work also included a new motor control center, electrical elements, and instrumentation to accommodate the plant expansion and conversion. Additionally the existing aeration basins received new Aerostrip diffuser systems, conveyance piping and a concrete-formed channel. Other work included improvements to the chlorine contact basin, influent pump station and digesters, and installation of service water booster pumps.

This originally estimated $6 million project was constructed under budget and ahead of schedule.