Design and Construction of a Bunker Fuel Transfer Pier at Melones Island, Panama

In 2009, Melones Oil Terminal Inc. (MOTI) embarked on a $90 million program to develop a 2-million-bbls capacity, bunker fuel transfer facility at Melones Island, a small rock outcrop located 8 nautical miles from the Pacific entrance of the Panama Canal. The MOTI facility comprises 16 storage tanks and a T-shaped pier configured for the simultaneous berthing of a 70,000-tonne dead weight tonnage (DWT) tanker and two 9,000-tonne DWT bunker transfer barges, or four bunkering barges. The marine structure consists of a 345-meter-long pier connected to the island via a 130-meter-long access trestle. The trestle length was selected so as to provide the required 15-meter water depth along the main berth without rock dredging. The pier structure consists of a series of breasting/mooring dolphins interconnected with modified AASHTO Type II pre-topped girders. When completed, the terminal will store and distribute bunker and diesel fuel to vessels transiting the Panama Canal. This paper describes the challenges associated with the structural design and construction of the marine facilities at the island site. Because of the soft and variable overburden layer between the seabed and underlying rock formation, the pile installation was the most challenging aspect of the project. Framing was selected to ensure structural stability during construction. The high-capacity concrete piles were socketed into the rock, driven to refusal, and anchored to the rock. The effects of pile slenderness on axial and bending capacity under berthing, mooring, and seismic conditions were thoroughly examined in the deep-water dolphins. Seismic effects were evaluated to ensure adequate deformation capacity and strength in piles and pile-deck connections. Pier construction was further complicated by the intrinsic offshore nature of the project and exposure to ocean swells. This translated into extensive and careful construction planning, spanning from the transportation, handling, and erection of precast piles and girders (some of which were as long as 42.5 meters) to the casting and curing of the concrete dolphin caps and the installation of surface features.