Construction Manager At-Risk Implementation for a Water Treatment Plant Granular Activated Carbon Filtration Project

T he City of Casselberry evaluated many alternatives to comply with the Stage 2 Disinfectants and Disinfection Byproducts (D/DBP) Rule compliance regulatory changes and selected implementation of granular activated carbon (GAC) filtration at its South Water Treatment Plant (WTP). The City performed preliminary planning on many different precursor removal and treatment methods, including ozonation, ultraviolet radiation, GAC filtration, and changing disinfection methods to chloramination. Following preliminary selection of GAC, pilot testing was performed to evaluate precursor removal effectiveness. Reiss Engineering Inc. designed the GAC improvements and continued its services throughout construction as part of the implementation team. Wharton-Smith Inc. was selected as a construction manager at-risk (CMAR) contractor to perform the required GAC treatment process improvements at the WTP. The CMAR process provided a reduced construction schedule and allowed the City and engineer to maintain a nonadversarial relationship with the contractor, essentially allowing all parties to act as a construction team. The team worked together to reduce time on shop drawing submittals, request for information (RFI) reviews, and field changes, and actively pursued value engineering options throughout construction of the required improvements. The team also added to the scope of the initial project to greatly improve it, while reducing the construction schedule and keeping the project within budget.