Westerly Wastewater Treatment Plant Centrifuge Replacement (OH)


Northeast Ohio Regional Sewer District (NEORSD) needed to replace dewatering centrifuges at their 26 mgd Westerly Wastewater Treatment Plant (WWTP).


NEORSD’s decision to use progressive design-build (PDB) project delivery was based on the need to move more quickly, save money, and promote collaboration—resulting in a better approach than possible with traditional design-bid-build (DBB). PDB also gave NEORSD full insight into the costs of the work to be done throughout the project. NEORSD selected a contractor (Kokosing) and a design engineer (Arcadis) as the design-build team. Throughout the procurement process, a critical feature was the conduct of numerous workshops discussing equipment specifications and vendor evaluation criteria.

As the design phase reached 60%, the DB team provided a guaranteed maximum price (GMP) to NEORSD and prepared all documents with enough detail to enable equipment suppliers to provide cost quotes and subcontractors to price their specific scope of work. The collaboration process among the engineering, construction, and NEORSD operation and maintenance (O&M) staff during development of the documents engaged all stakeholders, resulting in a design that improved O&M efficiency, utility cost savings, and safety. NEORSD saw the advantages of the PDB approach very clearly and became fully committed to the PDB delivery method, rather than reverting to design-bid-build. In addition, it was also imperative to maintain a risk profile throughout the project in order to identify, target, and mitigate risks.


The centrifuges were installed, and the refined process train came online more cost effectively and efficiently than would have been possible with the DBB approach. Because of the broad-based collaboration, the NEORSD team realized the significant benefits of a project achieving greater value when all parties are working toward the same outcome.