GAMBOA, Panama – The Rialto M. Christensen sits forlornly in dock, idle for one of the few times this year. A week ago it broke a gear which had to be custom-ordered from overseas. The wait cost a month.

C.J. Schexnayder
A Japanese-built 30-year-old mechanical dipper dredge is the work horse of the ACP.

This is not to say things aren’t hectic on the deck of this 30-year-old vessel. The break in the regular work schedule has given the crew an opportunity to make sure everything is in perfect working order for the upcoming challenge – dredging millions of cubic meters of material as part of the massive $5.25-billion expansion of the Panama Canal.

Of the 50 million cubic meters to be dredged as part of the project, the Panama Canal Authority (ACP) will handle 27 million cubic meters – 17 million cubic meters for widening and deepening the navigation channel in Gatun Lake, 6 million cubic meters deepening the Galliard Cut and 4 million cubic meters for the access channel from the new Pacific locks.

The current fleet includes two vessels you could safely call “warhorses.” The Rialto and the 64-year-old cutter suction dredge, The Mindi. Between them, the two dredges excavate approximately 2.5 million to 3.0 million cubic meters per year.

The Rialto M. Christensen is the canal’s mechanical dredge. Built in Hakodate Dock, Japan, in 1977, it cost $5.3 million. Two major refittings added more than $2 million to the vessel that is still the backbone of the canal’s dredging fleet.

The mechanical arm has a capacity of 15 cubic yards. It carries five barges with it to transport dredged material. The total cost of the barges, built in the mid-1980s, is almost $9 million.

The Rialto can dredge 650 cubic meters a day on average, with a max of 15,000 cubic yards per day. The dredge is also handy for digging up ships that run aground in the canal, which happens every few years, said Peter Marotta, the Rialto’s captain.

“It is designed for working here,” he said. “It can handle the hard material and the demands we have to put on it.”

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    The Rialto may be the front-line sailor in the canal’s dredge fleet, but the suction dredge Mindi is the aged veteran. Built by the Ellicott Machine Co. in Baltimore, Md. in 1943, it originally cost almost $7 million. It has been upgraded to the cost of $14 million since and refitted twice to the tune of $10 million more.

    Originally built as a diesel-powered vessel, it is now electric. It carries 2 pumps and can work at 12,000 horsepower. And, except when in dock for repairs, she still works 24 hours a day 7 days a week, Arias said.

    In fact the Mindi was originally designed and purchased to work on the 1930 expansion of the canal started by the U.S. Army but abandoned due to World War I.

    “It turned out she hardly worked on that,” Arias said. “But nobody had any idea the Mindi would still be around sixty-some years later to work on the expansion again.”

    The ACP is in the process of purchasing a second cutter suction dredge that will work alongside the Mindi for the expansion project but that will eventually replace her, Arias said.

    “The dredge we are considering is a mid-sized dredge by today’s standards,” Arias said. “It needs to be big enough to do the job but not so big it interferes with traffic.”

    Given the extensive period of service of the dredges, a key part of deciding what type of machine to purchase is looking into the future.

    C.J. Schexnayder
    The suction dredge Mindi was pulled out of service by World War II, but has been back on the job ever since.

    “We have to take into account not only what we are doing right now but what we think is going to happen over the next 20 or 30 years,” Arias said, “in terms of dredging and in terms of the canal’s use.”

    It’s the same system used with the previous mechanical dredge, The Cascades, that was put in service in 1915 and was finally retired in 1995. The Rialto was purchased in the late 1970s with the intent of eventually replacing it.

    And while there are no current plans to replace the Rialto, it will be getting a hand for the expansion effort. The backhoe dredger Il Principe arrived the first week of April. Its Liebherr 995 crane boasts a 25-meter reach, a 110-tonne capacity and can haul up 7.5 cubic meters of material each bucket load. The vessel is 60 meters long and 16 wide and is run by eight operators.

    Originally built in 2005, the dredge is owned by Jan de Nul Group of Belgium, which has been contracted for at least three years.

    It’s an important addition to the fleet for the expansion because it has the vertical reach necessary to excavate the deeper drafts needed in the navigation channels for post-Panamax ships, Arias said.

    The canal also has two drilling and blasting barges. The Thor is the 64-year-old veteran that was joined by Barú last year – one of the largest of its type in the world.

    The Barú, named after Panama’s only volcano, was designed by De Donge Shipbuilding and built by ACP’s Industrial Shipyard Division. It is 51 meters long and 15 meters wide and is equipped with four drilling rigs that can bore holes up to 30 meters in a single pass.

    Like the replacement system for the mechanical and suction dredges, the two vessels will work together for the expansion and the older one will be retired soon afterward.

    Although they are not part of the dredge fleet directly, the canal has two floating cranes that are still regularly used; the Hercules, which dates from World War I and the Titan, which came in service during Word War II.

    The canal will continue to operate while dredging occurs, one of the biggest challenges on the project. “Space is at a premium,” Marotta said. “We want to take up the least amount of space as possible so we always do our work parallel to the canal to allow shipping to continue passing through.” The Mindi is longer than a Panamax vessel with its barge attached.

    While there have been advances in technology and regular upgrades to the fleet, the basic concept of dredge work remains much the same as it was a century ago when the canal was built. A fact borne out by the fact the Rialto was only able to break the standing record of material excavated in an 8-hour shift in 2005 when it hauled up 760 cubic yards – a record set almost 80 years prior.

    “Even with all the upgrades and changes, we are still doing this work the way it was done when the canal was built,” Marotta said. “We are always looking for a better methodology, but the basic task remains the same and this is still the best type of tool to do this specific job.”