City Details Early Cost Estimate for the Inner Harbor Water Treatment Campus
The cost model, a contractor’s informed estimate, has been completed for the Inner Harbor Water Treatment Campus (IHWTC) – the City’s seawater desalination initiative. The cost model was completed by Kiewit, the Progressive Design Build (PDB) firm selected to design and build the IHWTC.
The current estimated construction cost for the IHWTC, which is based on 10% design completion, is $997 million.
The projected average monthly increase to the residential ratepayer in 2029 is $11.38, which is an increase of $1.42 per month above the $9.96 per month that was presented to Council in June of 2024. If successful with the U.S. Bureau of Reclamation grant application, the projected average monthly increase to the residential ratepayer will be $9.92, which is a decrease of $0.04 per month below the $9.96 per month that was presented to Council in June of 2024. Large volume users are estimated to see a monthly increase of approximately $463,000. Below are tables detailing the 10% design total project cost, annual operating cost, and the impact to the ratepayers:
This cost has remained top of mind during the design process, and every effort is being made to meet or improve upon the approved average monthly cost of water. As Kiewit advances the design, they will continue to refine the construction and operational cost. Kiewit has made significant enhancements to the operational cost through advanced operational technology, which will minimize energy usage and operational costs. This optimization of technology has lowered annual operating cost estimates from an initial operational cost estimate of $44 million annually to a current estimate of $32 million annually.
The current cost model is a Class 4 cost estimate, which has an accuracy range of between 50% above to 30% below this estimate. This range is industry-acceptable to the level of design that has been completed to date. The cost model will be further refined and updated as the design nears full completion. The iterative cost modeling process will culminate in a Guaranteed Maximum Price (GMP) of the facility’s construction and initial operation, coinciding with 60% completion of the design. The Council is expected to be presented with and vote on the GMP in December of this year.
The PDB process offers a more collaborative and cost-transparent project delivery model that aligns with the City’s priorities of managing public resources responsibly and delivering complex infrastructure efficiently. Under PDB, key cost snapshots are developed at specific design milestones – 10%, 30%, and 60%. This phased approach allows the City to monitor and influence project scope and expenditure in real time, culminating in the establishment of a GMP.
From December 2024 to June 2025, Kiewit worked closely with the City, their owner’s agent Freese and Nichols, and their internal and external engineering experts to develop a comprehensive basis of design detailing all critical needs of the project, perform detailed analysis of existing site conditions, and develop a 10% design. This information was used to develop the cost model.
“We’ve spent the last several months learning from extensive research, meetings with experts, navigating the permitting processes, and have used the information we’ve gained to focus our design scope, allowing a comprehensive 10% designed construction cost,” said Drew Molly, Chief Operating Officer of Corpus Christi Water.
An earlier opinion of probable cost was determined in late 2023 by Freese and Nichols and was created in advance of technical and facility design led by Kiewit. This probable cost was necessary to secure initial state funding and project planning. Fluctuations in estimated cost are a standard part of early design stages of the progressive design-build process, until a GMP is determined at the 60% design milestone.
To ensure fiduciary responsibility the City has employed an independent cost estimator to review the cost model. Those reviews will continue at each design milestone.
About the Project
The Inner Harbor Water Treatment Campus represents a vital component of the City’s long-term water management strategy. Seawater desalination provides a drought-proof water supply by converting seawater into fresh drinking water through advanced treatment processes.
This landmark facility is the result of years of careful planning and collaboration with local and state partners. The approach to this project focuses on three essential priorities that benefit the community: affordability, environmental sustainability, and reliability.
For more information about the Inner Harbor Water Treatment Campus project, visit https://bit.ly/3XRKev5 or contact Strategic Business Manager Rachel Esses at 361-826-7350 or rachele@cctexas.com.