Winzler & Kelly was the lead design firm selected for this design/build project to construct a surface transportation pier and shore side support facilities at San Nicolas Island in the Channel Islands off the southern California coast. This project is the first open-ocean, roll-on/roll-off cargo pier in the world. The project was managed by SouthWest Division for the NAVAIR Weapons Division at Point Mugu. The Navy’s team included a third party review by technical experts from the Naval Facilities Engineering Service Center at Port Hueneme.

The components of this project include:

• 85 meter by 10 meter, concrete, pile-supported pier extending from the shore
• 52 meter by 7 meter adjustable steel access ramp with supporting dolphins
• 5 mooring dolphins for positioning of the cargo barges
• Fendering system design
• Mooring analysis
• Operations building
• Cargo storage warehouse
• Site Improvements 

The initial and most complex phase of the design consisted of modeling the proposed mooring system and barge in the sea conditions dictated by the specification. Being the first offshore facility of this kind, this modeling required extensive analysis and review by ocean engineering and naval architecture experts from NFESC and the ocean engineering industry. Our modeling work included the analysis of several different mooring and berthing configurations. These configurations were developed using input from the Navy, the barge captain and crew, and the island operations personnel. This process revealed a necessity to balance the requirement to hold the barge steady with practical and safe methods. The more we tried to hold the barge steady, the larger the resulting line and structure forces became. The various configurations were analyzed for the motions of the barge and the loads imposed to the support structures.

The design work included the design of the movable ramp structure to facilitate loading and off-loading. The ramp is a 52 meter steel bridge structure that is supported and hinged at the fixed pier and supported by chains at the ocean end. The ramp can be raised 25 feet from the stowed position to the lowest operational position. The ramp structure is designed for HS20-44 loading and has been designed as a barge section so it can be lowered into the ocean for transport to the mainland for future maintenance. The lifting mechanisms are two hydraulic rams with heavy-duty chains supporting the ramp.

The fixed pier section is a concrete, pile-supported structure extending over 85 meters into the ocean.  The pier is designed per the latest Navy pier seismic design criteria (TR-2069-SHR, Design Criteria for Earthquake Hazard Mitigation of Navy Piers and Wharves.) The pier is also designed for HS20-44 loading and for operating a 250-ton crane. The pier includes lighting, safety rails and a catwalk system out to the mooring dolphins. The concrete pier consists of prestressed concrete piles; precast concrete pile caps; precast, pre-stressed girders; and a cast-in-place concrete deck.

The shore-side facilities include a new operations building for the pier with an office, work room, break room, bath facilities, and an observation platform. The site will be completely paved to provide a safe and efficient work area for the Navy. A transit shed will be constructed on the upper portion of the island for staging of equipment and materials to be on- or off-loaded onto the island.

Value Added by Winzler & Kelly

Winzler & Kelly’s participation on the team has allowed the Navy to explore a number of options for the barge landing that were not previously considered. This was due in part to our extensive off-shore marine and concrete pier design experience. This experience permitted our design team to model and analyze the barge motions at the pier and determine the amount and velocity of movement at the barge/ramp interface. This analysis allowed the design team, the contractor, the Navy’s technical personnel, and most importantly the Navy’s operational personnel to comment on and evaluate various mooring options for the project and to select the most advantageous solution to their needs.

Two major challenges were encountered during the design and construction of this project:

1. The first was in analyzing the barge motions and forces at the pier. The preliminary information from the Navy did not paint a clear picture as to the magnitude of the motions and forces and thus our design team analyzed several different configurations of the system.
2. The second challenge encountered was difficulty with the soils and the installation of the piles at the site. Original tests of the soils at the site indicated that concrete piles with steel stingers could be driven into the supporting rock formations. Several pile-driving experts analyzed the geotechnical data and indicated this was constructible. However, during the test pile program, the rock formations proved harder than originally planned. Our team then developed an alternate method of installing the piles that involved casting a steel pipe pile within our prestressed concrete piles and drilling the piles into the rock. A special drill was obtained that pulled the piles into the rock formation and then allowed us to grout the piles into place. This method allowed us to accurately install and anchor the piles into place without the need for removing large quantities of overlying sand from grout sockets under 35 feet of ocean.