FORD ISLAND WATERLINE REPLACEMENT

SOCIAL, ECONOMIC AND SUSTAINABLE DESIGN CONSIDERATIONS

Among the primary considerations for the project was the need to improve the efficiency and reliability of the Navy�fs Pearl Harbor water system. This project provided much needed carrying capacity as well as backup capability for the water system to maintain water service to all base activities. As a result of the new line, and with improvements to the overall system, the pumps driving the water system have been operating more efficiently due to the reduced system �gback pressure�h. The lower system operating pressure has basically resulted in lower energy consumption and greater delivery capability. NAVFAC, Hawaii estimates of energy cost savings attributed to the system improvements are currently about $50,000 per year.

The application of �gtrenchless�h construction methods used in this project also resulted in minimal impact on the environment. Of specific concern was the underwater crossing work that may have caused significant disturbance to the sediments on the Harbor bottom. It was imperative that the Harbor waters not be clouded with suspended sediment that may contain hazardous or toxic materials. The pipeline materials used in the project were selected for their corrosion resistant properties, with the intent of providing maximum service life. Furthermore, serviceable items such as valves and expansion couplings are installed in concrete vaults that allow service and replacement without the need to excavate large areas, reducing future impacts on the surrounding areas.

COMPLEXITY

Various design elements were considered as part of the modified HDD method, including vertical alignment for minimum pipe bend radius, pulling loads on the HDPE pipe string, hydraulic design to avoid a mid-length high point, and permanent harbor bottom ballast to maintain the long term stability of the installed pipeline.

Containment of HDD drill fluids at the mid-harbor exit locations required adopting special provisions to prevent contamination of the harbor waters.

Borehole stability, and heave and hydro-fracture potential were assessed for various drilling fluid scenarios. Risk of consequential damage to the adjacent pilesupported Admiral Clarey Bridge from potential hydro-fracture or borehole collapse was also evaluated using finite element analysis of combined pipe and bridge soil-structure interaction, confirming HDD to be the preferred solution as compared to underwater �gcut and cover�h (trenching) methods. Construction observations were also vital for project success, including offshore Tru-Tracker. drill head navigation to insure proper bore hole alignment, avoiding encroachment into the bridge foundation support zone and eliminating high points in the smooth sweeping pipeline profile. Constant monitoring of pull loads was also required to avoid overstressing the pipe string, which could potentially permanently impair the pressure rating and longevity of the waterline. Surface barge staging operations, with an assist rig to provide support of the pipeline during the over water staging and pipe string insertion operations, were required. Also, dive operations for the final underwater splice connection were also required to complete the installation of the submarine line.

MEETING AND EXCEEDING THE CLIENTS EXPECTATIONS

FAINC and the design team were fully engaged in support of the project from inception, through development, and final completion, partnering with both the client (NAVFAC Pacific) and the owner (NAVFAC, Hawaii), as formalized in the FACD effort. As with most projects the construction cost was a major concern. It was a significant challenge to meet project objectives within the available budget. For this project, the original programming documents had set the estimated construction cost (ECC) at $12.6 million. The final design construction cost estimate was $12.1 million, and the actual final construction cost was $12.0 million. Much of the cost savings can be attributed to the innovative design of the under channel pipeline crossing.

The greatest long-term benefits to the Navy will be from more energy efficient operations and enhanced system reliability. The new water system installed on Ford Island will support proposed developments that will transform the island into a vibrant commercial, visitor and operations center within Pearl Harbor.

The design team completed the project on time and within the design budget, earning a Certificate of Appreciation from the Navy for "outstanding design and engineering services, responsiveness and highest level of professionalism." The project was put out to bid on schedule in 2002, with construction commencing, also as scheduled, in 2003. The project was substantially completed in 2005. The waterline was operational and ready to support several key Ford Island facilities including the National Oceanic & Atmospheric Administration Pacific Regional Center and Ship Operations Facility (under construction), the Pacific Warfighting Center (in design), and the Pacific Aviation Museum (under construction).