VESSEL REVIEW | NSF Discovery Pier – Loading/offloading barge to facilitate resupply of US research stations in Antarctica
The US National Science Foundation (NSF) has begun operating a new floating steel barge pier at its McMurdo Research Station in Antarctica.
NSF Discovery Pier was built by Gunderson Marine and Iron of Portland, Oregon, to a design developed jointly by engineering firm Moffatt and Nichol and the Marine Design Center of the US Army Corps of Engineers (USACE). Contract design and mooring analysis in support of the project was provided by naval architecture firm Glosten.
The 100-metre (330-foot) long barge pier will be operated by the USACE in support of the NSF. It has since replaced the NSF’s ageing ice pier that had been facilitating the transfer of cargo, fuel, and personnel from visiting ships to McMurdo Station year-round.
Permanent solution replacing fragile and unreliable ice piers
“The barge pier replaces the increasingly unreliable ice pier for vessel resupply operations,” Stuart Gregory, Transportation Manager of the US Antarctic Program under the NSF, told Baird Maritime. “The modular causeway system required a percentage of cargo vessel capacity and added about a week to the schedule for causeway construction and demobilisation. With NSF Discovery Pier, the US Antarctic program will be able to use more of the cargo vessel capacity for station resupply and retrograde and will reduce the cargo vessels time on station.”
Gregory added that barge pier bridges will allow the offload of heavier cargo such as construction equipment. Previously, if cargo heavier than 50 tons was to be offloaded, the modular causeway needed to be used.
“For decades, the US Antarctic Program built and maintained ‘ice piers’, which were essentially huge floating ice cubes. Ice piers were generally reliable and used for many seasons until 2012, when the ice pier failed prior to vessel operations. The only contingency option was to use a US Army-operated modular causeway to execute vessel resupply that season."
Gregory also noted that there were several other ice pier failures in the years that followed.
Durable platform built to withstand severe ice conditions
In contrast to an ice pier or a temporary modular causeway, the barge pier was designed to remain in service for at least 20 years before any shipyard maintenance is required.
The new barge pier has a raked hull design that allows it to rise as surrounding ice forms. As the pier rises, it will eventually break the ice forming below it and drop back into the water. Gregory said this design feature protects the pier from being crushed by ice throughout the Antarctic winter.
“The mooring system is also unique as it uses four struts with energy cells to connect the barge to pile caps on an ice shelf,” Gregory told Baird Maritime. “There are also two bridges that allow vessel operations traffic and personnel to move between the barge and the ice shelf.”
The barge pier has no permanent electronics. The only electronics are temperature data logging equipment along the length of the 70-foot (20-metre) piles embedded in the ice shelf. The temperature profiles will be used to monitor the health of the mooring system.
“The deck is open with no permanent equipment to provide a smooth flow of trucks/trailers on and off the barge pier,” added Gregory. “There is bull rail around the perimeter of the deck to provide a safety barrier for equipment operating on the deck. The open deck also allows snow to blow off during the winter instead of building up large drifts that need to be cleaned off prior to operations the following January.”
Overcoming design issues typically encountered during prototype development
Gregory said that, as the barge pier was a new type of vessel not previously employed by the NSF, its design and construction presented a number of challenges. First, the pier needed to be able to survive in the Antarctic climate year-round for 20 years. It also needed to be large and thick enough to support offload/onload of millions of pounds of cargo each summer.
The team had to ensure the pier was sized right to enable a nearly 10,000-mile (16,000-kilometre) tow from Portland to McMurdo and then mooring it in a location where nothing was permitted to touch the seafloor and the barge is permanently moored to an ice shelf.
Lastly, development of the barge also needed to fall within budget.
“The design of the bridges between the barge pier and the ice shelf changed the most from early concepts to final construction,” said Gregory. “Originally envisioned as fully assembled bridge sections, the final bridges are modular truss bridges assembled on site. The primary drivers for the design change were on-site crane capacity limitations and cost.”
The project team learned that operating in extreme environments requires a unique approach to every part of the design, and the barge was just one piece of what Gregory said was a bigger puzzle.
“Planning all installation activities in advance of arrival on-site at McMurdo and creating efficiencies in design (e.g., mooring connection pins, fender installation) that limit risk during installation in the Antarctic environment lowered project risks during installation,” he told Baird Maritime.
NSF Discovery Pier will be moored in Winter Quarters Bay at McMurdo Station. Each year between January and February, it will be used for offloading/onloading large quantities of containers, breakbulk cargo, and rolling stock to resupply McMurdo and South Pole Stations.
The barge pier was towed from Portland to Antarctica by a tug operated by New Orleans-based TradeWinds Towing. The voyage to Antarctica included a stop at Lyttelton Port in New Zealand.
