Ports & Terminals

WIMOs Webinar Compares Marine Terminal Design, Construction

A webinar hosted by Women in Maritime Operations (WIMOs) April 24 gave members the opportunity to learn about terminal design and to compare and contrast designs used on the river system with those used for seaports.

Nicole Siems, senior designer at VAA LLC, a multidisciplinary engineering, planning and design firm based in Portsmouth, Minn., and Lina Maria Garcia Martin, the company’s marine department manager, were the guest speakers.

Siems noted the importance of new technology in designing terminals. Instead of using field notes, drawings and photographs, most projects are now completed with the help of 3-D software, including a scanner that helps to capture information about existing structures in the field.

“Based on this information, we know the size, elevation, the proximity to existing structures, and we’re able to design around them,” Siems said.

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Siems and Garcia Martin took participants on a virtual tour of terminals that VAA has been involved in designing.

They discussed three types of designs: bulkhead, floating dock and pile supported.

“Each terminal is unique,” Garcia Martin said, noting that designers must take into consideration its location, soil conditions, likelihood of corrosion and the potential for natural disasters, such as fires, explosions, hurricanes and tsunamis.

Siems began the tour with a video of a 3-D scan used to create a terminal for the St. Paul (Minn.) Port Authority that is operated by a fleeting service that cleans and turns around barges for their next use.

VAA designers chose a closed fill bulkhead design for this project, which includes an earth retaining wall, steel sheet piles, anchors/tie rods, a sheet pile cap, mooring points with bollards and continuous fenders.

“In many cases this design is faster to build,” she said. “It’s cheaper. It helps protect shorelines from erosion.”

Because most of the structures are underground, it also protects them from damage and erosion, so the facilities typically require less maintenance and repair over time.

When designing a bulkhead design for a terminal, designers must think about what the terminal will be used for.

“Dock design needs to facilitate operational use,” Siems said, adding that the type of equipment used for transloading or cleaning, how barges leave and enter the berth, direction of travel and how crews enter and exit are all taken into consideration.

“We want to improve our clients’ processes and make sure everyone is able to operate safely and efficiently,” she said.

Garcia Martin then showed a 3-D scan from an unidentified riverport in the central United States where a floating dock was designed because the water at the site may fluctuate up to 60 feet in elevation.

“Other types of docks can’t do that and may be unusable in high water or low water,” she said.

An additional benefit is that the floating dock design comes preassembled, allowing easy installation. Under certain circumstances, the floating dock design can be the most cost effective, especially because of its flexibility.

“It can be reconfigured or changed to fit operational needs, such as adding slips or adjusting the layout of the dock,” she said.

The final river terminal on the virtual tour was on the Lower Mississippi River in Myrtle Grove, La. This open pile supported terminal included an unloading dock for barges, process plant for cargo and distribution, including both rails and a loading dock for larger, ocean-going vessels.

A pile supported design was important for accommodating large vessels with a deep draft, Garcia Martin said.

“These types of structures can provide more flexibility in terms of the types and sizes of vessels that can be accommodated,” she said.

The design needed to provide access trestles for crews to be able to safely access docks. Pile-supported designs have more structures in the water but don’t have to use as many bulkheads and sea walls.

Piles often require coatings, especially when exposed to sea water, which corrodes at 10 times the rate of fresh water, Garcia Martin said.

Siems and Garcia Martin also compared the river terminal designs to two ocean terminal designs, in the Bahamas and in Panama.

VAA provided ship dock repairs to the Morton Salt facility at Great Inagua, Bahamas, after it was hit by Hurricane Joaquin, a Category 4 hurricane in September 2015. The hurricane had a 20-foot storm surge and wind speeds of up to 70 mph.

Parts of the terminal lay in ruins on the bottom of the ocean following the hurricane. Designers worked with the company to create an open pile terminal design capable of serving ships from 8,000 to 53,000 metric tons. Components were manufactured in the United States from prefabricated steel and precast concrete.

A challenge in construction was that the designers could not drive piles where debris was located on the seabed.

Impact hammers mounted on barges were used to drive piles with a jacket construction that allowed all the pre-fabricated parts to fit together, “kind of like Lego,” Garcia Martin said.

Another concern was that since only one crane was available at the location, all parts had to be pre-designed in sections capable of being lifted by that crane.

Following construction, it was necessary to demolish the old loading platform, making sure that none of it would collapse atop the new structures.

Five months after construction was complete, Hurricane Irma, a Category 5 storm, made a direct hit on the facility, with a storm surge of 39 feet and top winds of 130 mph. Minor components designed to disconnect, such as the catwalks, were washed away, but the main structural components were unaffected, Garcia Martin said.

The final stop on the virtual tour was a liquid terminal for oil and gas in Puerto Armuelles, Panama. VAA created an open pile-supported terminal for the location from prefabricated steel after the previous structure was destroyed by a ship impact.

The design challenge included allowing for access by “super tankers,” which have a 90-foot draft and are longer than the Eiffel Tower is tall, Garcia Martin said. The design also had to accommodate potential seismic and tsunami issues, so geotechnical exploration was necessary.

“Every component had to be fabricated in the U.S. and brought back to Panama on barges,” Garcia Marin said.

In addition to the basic design methods the two speakers addressed, Garcia Martin said it is also possible to combine design elements, such as with a bulkhead terminal that also has a pile-supported structure. Such combinations are frequently seen in the design of container terminals, Garcia Marin said.

Regardless of the eventual design chosen, she added that it is important for companies to work with an engineering firm that has planning and construction expertise and is able to accommodate all environmental standards required for each location.

Garcia Martin ended the conversation by speaking about the efficiency of water transportation compared to other modes and its relative environmental friendliness, reducing overall emissions.

“Marine terminals provide a stable form of transportation, and that’s why I’m very passionate about this,” she said.