City of Hays, Kansas Hays, Kansas, United States

Innovative design-build team delivers significant savings

Upgrades to meet discharge limits

As part of a design-build partnership, CAS Constructors, an Alberici Enterprise, is upgrading the Chetolah Creek Water Reclamation and Reuse Facility to replace aging infrastructure and meet stricter discharge limits. Upgrades to the 65-year-old plant include the construction of a new liquid process train, improvements to the biosolids treatment process, complete electrical upgrades, and expansion to the City’s reuse storage capacity.

Innovation to the Rescue

The City of Hays was unable to agree to a guaranteed maximum price (GMP) with their original design-build team, forcing the City to take the job back to the market for fixed-priced design-build bids. The CAS Constructors team’s solution saved $4 million from the original design-builder’s GMP. Accepted cost savings ideas include a different approach to the new liquid process train, selective repurposing of existing processes, and expanding an existing water reuse pond at the City’s golf course rather than adding large water reuse storage tanks at the plant.

Liquid Process Train Improvements

During construction, CAS demolished unused portions of the operational plant to build a new liquid process train, including a new influent pump station and headworks building. Inside the headworks building, trash removal is done via drum screens, grit removal is completed using headcells, along with grit washing and classifying. The process train also includes a single 185-foot diameter aeration basin that will contain four submersible mixers and 24 submersible air diffusers, two 75-foot-diameter primary clarifiers, and a tertiary disc filter housed in a new building. The existing sand filter room will be retrofitted for primary disinfection with four new UV in-line chambers.

Biosolids Treatment Improvements

To treat biosolids, the CAS Constructors team will convert two existing aeration basins to digesters and install new sludge pumps that will pump to a new centrifuge. The solids will then be dewatered in existing drying beds and land applied.