Rapid Pier Delivery Using Precast Concrete Components

In July 2008, a new pier for offloading coal was commissioned at the Morgantown Power Generation Plant in Maryland, on the US eastern seaboard. The new pier, measuring 495 ft long x 54.5 ft wide, is designed to support a coal unloading machine capable of handling barges up to 20,000 DWT. Contractual arrangements with the coal supplier dictated the need to have the pier ready for operation by July 2008, only 10 months after initiation of the pier design. Permitting revisions, supplemental site investigations, full design of the pier and conveyor foundations, and the construction of the entire pier and conveyor system had to be accomplished within this very tight schedule. To accelerate the project delivery, a modified design/build approach was utilized wherein the design consultants worked closely with the constructor to develop a structural scheme that could be procured, fabricated, and erected within a highly compressed timeframe. The design solution was a unique modular precast concrete structure that minimized the amount of cast-in-place concrete work. This approach allowed the fabrication of precast units offsite, which could then be assembled rapidly onsite once the piles were driven. Critical path elements such as piles and crane rails were pre-ordered, while design of the remaining components was still underway. One unusual challenge overcome for this project was developing a connection detail to allow precast concrete pilecaps to be used with hollow prestressed concrete batter piles. This innovative approach to the design and detailing facilitated construction in winter weather and significantly shortened the construction schedule. This $46M project was successfully completed within schedule and budget, and the first barge was unloaded in July 2008 as per contractual obligations. The project subsequently won a local award from the American Council of Engineering Companies.