Dredging the Panama Canal

Brantz von Mayer and The Writers for Hire

Despite its relatively short distance, the Panama Canal serves as one of the greatest shortcuts to world commerce. Thanks to engineering ingenuity, ships sailing between the Atlantic and Pacific coasts of the American continent can save up to 8,000 nautical miles by taking this shortcut through the isthmus of Panama, instead of having to sail all the way around southern tip of South America. Vessels from one coast of North America bound for the other coast of South America shave 3,500 nautical miles off the voyage, and those traveling between Europe and Asia or Australia eliminate 2,000 nautical miles from the journey. 1   As an added bonus, shipping can avoid sailing around Cape Horn, the treacherous waters between the Southern tip if the American continent and Antarctica, infamous among sailors for its violent seas and unpredictable weather patterns.

This man-made waterway across the Panamanian isthmus runs almost 51 miles from ocean to ocean. At a latitude of 9° N, the canal is situated at one of the lowest points along the North American Continental Divide. It runs straight south from its Atlantic entrance at Colón for 10 miles, then east/southeast until it reaches the Pacific side near Balboa at the Bay of Panama in the Caribbean Sea, roughly 25 miles east of Colón. 2,  34

The Panama Canal is a complex system of artificial lakes; natural, man-assisted, and artificial channels; and three sets of locks. 5   To state that its undertaking was immense is putting it lightly: construction took place in two stages by two completely different groups, at an estimated cost ranging from $375-$400 million and 22,000-27,000 lives.67

French Foundation ~1881-1889

In 1879, Ferdinand de Lesseps and the French Compagnie Universelle du Canal Interocéanique proposed a sea-level canal through the Panamanian isthmus, based on his recent success with the Suez Canal in 1869.8, 9, 10 The French organization began construction in 1881, employing bucket ladder dredgers, the earliest form of mechanical dredger that ran a continuous chain of buckets around the rigid frame. 11 The Catskill Archives, dated February 1885, provides an early account of the dredging process:

The machinery of the dredge is mounted on a scow one hundred feet long, sixty feet wide, and twelve feet deep. There are eight engines, arranged in four pairs, for operating the machinery. The main engines are for driving the buckets which do the digging, and are of 250 horse power, having Myers’ adjustable cut-off. The belt from the engine runs to the top of the bucket tower to a pulley eight feet in diameter, which drives compound driving gear, connected with the upper tumbler shaft, which is ten inches in diameter. This shaft moves a thirty-six inch square drum, over which the buckets pass when they dump their load into the hopper. The bucket tower is forty-five feet high above deck. There are thirty-eight buckets, with a capacity of one and a half cubic yards each. From sixteen to eighteen buckets full of dirt per minute are discharged into a hopper attached to a cast iron elbow near the top of the tower. This elbow is five feet four inches in diameter where it connects with the hopper, and thirty-six inches in diameter where it connects at the lower end to the discharge pipe, which is attached to the elbow. This pipe is made of boiler iron and is one hundred and fifty feet long. The distance the mud falls, the position in which it strikes, and the inclination of the discharge pipe give the mud a velocity of from 1,300 to 2,000 feet per minute through the pipe, according to the kind of material which is being dug and discharged. The discharge pipe is supported by a derrick which stands on the scow. Water is pumped into the hopper by a pair of ten inch pumps from the canal through a seven inch pipe which passes through the bottom of the boat and extends to the hopper, at top of bucket tower. A second pair of engines of thirty horse power raise and lower the ladder that supports the buckets; they are attached to a drum for that purpose. There is a hinged joint in the ladder outside of the derrick, for the purpose of operating one section of ladder independent of the other. A half inch cable connects the drum to the outward end of the lower section by two bails. The endless chain to which the buckets are attached is made of horseshoe iron 1-and- 1/8 inches by 9 inches. Another pair of spud and gypsy engines of thirty horse power is used for raising the spuds and feeding the buckets. The dredger rests upon the spud, upon which it can be revolved without stopping the dredging buckets, thus enabling the operators to dig from side to side at will. A chute connects with the hopper, and is boarded on the sides to prevent the mud or water from falling upon the deck. The fourth pair of engines, also of thirty horse power, is connected to a windlass for snag pulling. The engines are all supplied with steam from one set of three boilers, and will require only about two tons of coal each day. Six men, including a superintendent, run the entire machine. Capacity of the dredger, 1,000 cubic yards per hour.12

Unfortunately, this new project turned out to be nothing like Suez, and the French company was completely unprepared for the undertaking. While the sandy terrain made dredging a Mediterranean sea-level canal a straightforward accomplishment, the extreme topographical variations across Panama caused countless engineering quandaries. 13   By 1884, the project was not progressing on schedule. The dredging machinery was inappropriate for the landscape, too small and too light for the grueling work, especially through dense rock and sticky clay. The construction crew had a poor spoil disposal system too close to excavation sites, which caused earth slides and repeated work.14, 15In addition, the workforce under the French leadership experienced very high turnover—as much to do with disease and death as with horrible working/living conditions. 16, 17, 18

In 1887, the decision was made to scrap plans for a sea-level canal in favor of a lock system as a means to both curtail costs and solve topographical complications.19, 20 By this point, however, public opinion had shifted: the project was doomed, and investors backed out. Hampered by engineering challenges and crippled by financial difficulties, the French company dissolved and ceased work in 1889. Despite reorganizing into a new company in 1894, the French project received no further funding or support from the general public or the government. In the end, the company—and its ancillary capital, including machinery and infrastructure—was sold to the United States. 21, 22

Despite the relative failure of the French attempt, their work was anything but ignominious. Even with the cards stacked against them, they still managed to excavate more than 59 million cubic meters of Panamanian earth. In addition to providing this engineering “head start,” the French organization had also established housing and hospital quarters, upon which the American workforce expanded when it took over operations. 23 Perhaps most importantly, the French experience taught the American engineers what not to do.

American Acquisition ~1904-1914

The United States bought the French company’s assets (including seven of the original bucket ladder dredgers) for $40 million. 24   Proverbial keys changed hands in a brief ceremony on May 4, 1904; the first American steam shovel began work in November of that year under the leadership of the United States Army Corps of Engineering. 25,, 26

The first major divergence from the French strategy was changing the engineering plan to a lock-style canal. American engineers realized the folly of a sea-level canal: the difference in tidal ranges at each end of the canal (up to 20 feet at the Pacific and only 1 foot at the Atlantic), coupled with well-known and severe river flooding, meant that a sea-level option would be more expensive to build/maintain and more dangerous to traverse. 27

The American force also had the benefit of more suitable machinery. The evolution of more powerful engines made it possible for increasingly larger pumps that could move increasingly more material. The French had relied on the bucket ladder dredger, which proved an outdated technology ill-suited for the Panamanian terrain. The Americans switched to the more efficient hydraulic cutter suction dredger with a rotating cutter at the end of a suction line. Because of the ability to change the edges of the rotating blades, this type of dredger can be adapted for cutting into various materials.

The United States cargo-and-passenger ship Ancon was the first vessel across the Panama Canal on, on August 15, 1914. 28 The Panama Canal was controlled by the United States until 1979, when control passed to the Panama Canal Commission, a joint United States-Panamanian agency, and complete control passed to Panama (Panama Canal Authority) December 31, 1999. 9

Establishing the Infrastructure

As soon as the Americans assumed leadership, they revamped several key elements of infrastructure. The French workforce had been decimated by disease: statistics cited in a 1913 issue of Popular Mechanics noted that, at any given time, 60% were unable to work. The Americans instituted from the start a “Sanitary Corps” to eradicate yellow fever, malaria, and bubonic plague by ridding the isthmus of disease-carrying mosquitoes, fly’s, and rats. 30, 31 Thus fortified, the workforce (at times topping 40,000) 32 was able to concentrate on construction.

The Americans completely renovated the Panama Railroad (finished in 1855) with heavier track and upgraded bridges to accommodate more powerful engines, freight cars, dump cars, and refrigerator cars. This served a dual purpose: bringing in workers and supplies and taking out excavated spoil. 33, 34 The renovation enabled the development of an efficient spoil disposal system, with excavated earth dumped far enough away from the dredging site to prevent slides from refilling any of the excavation sites.35 The railroad also paved the way for the “high quality of American heavy machinery” 36 that made the United States venture in Panama a success: inventions originally developed for the burgeoning rail United States industry were adapted for use on this enormous excavation.

As the American workforce learned early on, the Panamanian topography required machines that could function effectively in a variety of terrains and conditions. The switch to the cutter suction dredger, replacing the outdated bucket ladder dredger of the French era, was a technological breakthrough. Even civilians noticed the difference, as summed up by one visiting US journalist: “A Suez dredger was put to work at a certain spot. After fifty days she was withdrawn, and one of ours took its place, and did in five days as much as the other had done.”37

The fleet required to complete the dig was immense; to fill the need, a number of American heavy-machinery companies played were enlisted to custom-build dredgers, dredger engines, and other dredging equipment. Baltimore-based Ellicott Machine Corporation crafted six of these machines, including a hydraulic pipeline model that could clear 750 cubic yards (573 cubic meters) of spoil per hour. (As a comparison, the salvaged bucket ladder dredgers that accompanied the American acquisition excavated 15 cubic feet [.4 cubic meters] of material to a depth of 45 feet [14 meters].) Other suppliers included New York’s Haywood Company, Froment & Company, and Atlantic Gulf & Pacific Company; A. L. Ide & Sons of Springfield, IL; and Baldwinsville, NY-based Morris Machine Works.38, 39

In fact, Ellicott’s products proved their worth and their lasting power: their cutter suction dredger MINDI joined the Panamanian maintenance crew in the 1940s and was still in work until 2011, when it was replaced by a new dredger built by IHC Beaver Dredgers of Holland.40, 41

Main Engineering Components

Excavating Gaillard Cut (originally known as Culebra Cut), the point at which the Canal passes through the Continental Divide, took 9 years of near-constant digging through dangerous mountainous terrain. Although the Cut is less than 9 miles long, some 100 million cubic yards of spoil was removed and then used to “create land” for a number of related projects, including a 3-mile-long causeway in Panama Bay, the Balboa townsite, the Fort Amador military reservation, and sites for locks and dams.42

Because of the magnitude of the excavation here, earth slides were a constant danger. Heavy rains weakened the already-precarious landscape, often pouring mud and rock back into cleared areas and reversing months of headway. The original engineering at Gaillard Cut planned for a width of 670 feet at the top; however, because of the instability of the earth along the sides of the Cut, the end result was almost three times as large.43 Slides necessitated an increase in the amount of excavation within the Cut and the repeatedly altered cross-section of the canal directly accounted for excavation increases of 15.3 million cubic meters over the original estimate.44 The infamous Cucaracha slide of 1907, one of the most destructive in Gaillard Cut, earned the characterization of “a tropical glacier — of mud instead of ice.” 45 After years of continual slide, during which millions of cubic meters of spoil poured back into the canal excavation, engineers decided to flood the cut and finish the work with dredgers—including, incidentally, the antiquated French ladder dredger “Marmot.”46

The engineers were, in one way, fortunate that the amount of material excavated from Gaillard Cut was so vast. Spoil reclamation became a ready resource for other construction needs along the Canal. One such need was the damming of the Chagres River.47 To solve the well-known problem of severe flooding along the Chagres River, engineers constructed a monstrous earth dam across the river at Gatún. The resulting Gatún Lake, at the time the largest manmade lake in the world, was able to accommodate floodwaters and became more than 20 miles (30 km) of the canal route.48

Gaillard spoil was also used in the creation of the three systems of locks, built between 1909 and 1913. 49 The three-stage Gatún Locks, 1.2 miles (1.9 km) long with a lift of 85 feet (26 meters), were constructed with concrete comprised of rock excavated from the Gaillard Cut. The single-stage Pedro Miguel Locks, 0.87 mile (1.4 km) long with a lift of 31 feet (9.5 meters) up to the main level of the canal, include an earthen dam with a concrete core wall. The two-stage Miraflores Locks, 1.1 miles (1.7 km) long with a lift of 54 feet (16.5 meters), involve two dams constructed in part with Gaillard spoil that created a small lake. 50, 51, 52

“The locks have been called the structural triumph of the Panama Canal and are a unique aspect of the waterway. At the time of their construction, their overall mass, dimensions and innovative design surpassed any similar existing structures, and they are still considered to be an engineering wonder of the world… After more than 80 years of service, the concrete of the Panama Canal locks and spillways is in near perfect condition, which to present-day engineers is among the most exceptional aspects of the entire Canal.”53


The dredging of the Panama Canal is a proverbial work in progress. Because many banks have never attained their angle of repose (at which earth slides no longer occur), continual dredging work is required to clear earth slides to maintain safe, navigable passageways. Silting and sedimentation, common to moving bodies of water, also require continual dredging to accommodate the draft of ship hulls.54

Dredgers never want for work in the Canal. In February 2004, The Panama News reported a new record: 7,800 cubic yards of spoil were dredged from the bottom of Gatun Lake in an eight-hour shift, breaking a 1916 record of 7,700 cubic yards. This feat was the product of the Japanese-built Christensen, the world’s largest dipper dredger, part of the Panama Canal’s maintenance crew since 1977.55

In addition to “regular” maintenance, several major enhancement projects have been commissioned over the years that enlisted the help of dredgers. In 1935, the first significant improvement on the Canal was the installment of Madden Dam at Alajuela Lake, to serve as additional rainy-season storage of Chagres floodwaters that are, in turn, used as a source of hydroelectric power. 56, 57

Gaillard Cut has benefited from major expansion, first during the 1950s and again between 1992-2002. 58 This latter project widened and deepened the channel to enable steady two-way traffic of ever-larger cargo ships. Before this expansion, these enormous vessels (known as “PANAMAX” ships) could only pass through the Cut in a one-way flow.59

“Although the Panama Canal can accommodate ships carrying up to 65,000 tons of cargo, stores, and fuel, modern ocean vessels can carry more than 5 times that amount.”60 Hence the need for even greater expansion: A current expansion project to the tune of $5.25 billion will dredge more than 50 million cubic meters of material. Begun in 2010 and anticipated to be complete in 2015, this expansion will to allow greater draft and width for the ever-increasing size of commercial cargo ships. Dredging International of Belgium won the bid to widen (to 715 feet) and deepen (“to 51 feet below maximum level of the mean low water mark”) the Pacific entrance to the canal. Expansion will also include dredging 14 million cubic meters of material at the Atlantic entrance.61, 62

; Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

“The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

Smithsonian Institution Libraries Exhibition: “Make the Dirt Fly!”: http://www.sil.si.edu/Exhibitions/Make-the-Dirt-Fly/engineeringicon.html

Wikipedia entry, The Panama Canal: http://en.wikipedia.org/wiki/Panama_Canal#cite_note-canalussage-0

Panama Canal Authority: http://www.pancanal.com/eng/general/canal-faqs

History.com: “Panama Canal Open to Traffic”: http://www.history.com/this-day-in-history/panama-canal-open-to-traffic

“The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

10 History.com: “Panama Canal Open to Traffic”: http://www.history.com/this-day-in-history/panama-canal-open-to-traffic

11 Modern Marvels, Season 11, Episode 38, Aired 8/3/05

12 The Catskill Archive: “American Dredgers on the Panama Canal”: http://catskillarchive.com/rrextra//pcdredge.Html

13 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

14 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

15 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

16 “The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

17 Modern Marvels, Season 11, Episode 38, Aired 8/3/05

18 Popular Mechanics: “The Wonder Story of the Panama Canal”: http://www.popularmechanics.com/science/4212223?click=main_sr

19 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

20 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

21 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

22 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

23 “The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

24 Modern Marvels, Season 11, Episode 38, Aired 8/3/05

25 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

26 “The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

27 “The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

28 History.com: “Panama Canal Open to Traffic”: http://www.history.com/this-day-in-history/panama-canal-open-to-traffic

29 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

30 Popular Mechanics: “The Wonder Story of the Panama Canal”: http://www.popularmechanics.com/science/4212223?click=main_sr

31 “Panama Canal Facts in Brief”: http://erwin.bernhardt.net.nz/america/panamacanalfacts.html

32 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

33 History.com: “Panama Canal Open to Traffic”: http://www.history.com/this-day-in-history/panama-canal-open-to-traffic

34 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

35 Linda Hall Library of Science, Engineering & Technology: “The Panama Canal”: http://www.lindahall.org/events_exhib/exhibit/exhibits/civil/infrastructure.shtml

36 Smithsonian Institution Libraries Exhibition: “Make the Dirt Fly!”: http://www.sil.si.edu/Exhibitions/Make-the-Dirt-Fly/dirtfly.html

37 The Catskill Archive: “American Dredgers on the Panama Canal”: http://catskillarchive.com/rrextra//pcdredge.Html

38 Modern Marvels, Season 11, Episode 38, Aired 8/3/05

39 Construction Equipment Guide: “Panama Canal: The Big Dig of Central America”: http://www.constructionequipmentguide.com/Panama-Canal-The-Big-Dig-of-Central-America/7868/

40 Ellicott: “Government Agencies Involved In Dredging”: http://www.dredge.com/dredging-links.html

41 ENR.com: “Belgian Firms Snags $177M Panama Canal Dredge Contract”: http://enr.construction.com/news/transportation/archives/080404.asp

42 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

43 Linda Hall Library of Science, Engineering & Technology: “The Panama Canal”: http://www.lindahall.org/events_exhib/exhibit/exhibits/civil/culebra.shtml

44 “The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

45 Smithsonian Institution Libraries Exhibition: “Make the Dirt Fly!”: http://www.sil.si.edu/Exhibitions/Make-the-Dirt-Fly/dirtfly.html

46 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

47 Panama Canal Authority: http://www.pancanal.com/eng/history/murals/index.html

48 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

49 Panama Canal Authority: http://www.pancanal.com/eng/history/history/end.html

50 “The Panama Canal”: http://www.eclipse.co.uk/~sl5763/panama.htm

51 Wikipedia entry, The Panama Canal: http://en.wikipedia.org/wiki/Panama_Canal#cite_note-canalusage-0

52 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

53 Panama Canal Authority: http://www.pancanal.com/eng/history/history/index.html

54 The Panama News: http://www.thepanamanews.com/pn/v_10/issue_07/business_01.html

55 The Panama News: http://www.thepanamanews.com/pn/v_10/issue_07/business_01.html

56 “Panama Canal Facts in Brief”: http://erwin.bernhardt.net.nz/america/panamacanalfacts.html

57 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/440784/Panama-Canal

58 “Panama Canal Facts in Brief”: http://erwin.bernhardt.net.nz/america/panamacanalfacts.html

59 Encyclopedia Britannica entry, The Panama Canal: http://www.britannica.com/EBchecked/topic/223518/Gaillard-Cut

60 Modern Marvels, Season 11, Episode 38, Aired 8/3/05

61 ENR.com: “Belgian Firms Snags $177M Panama Canal Dredge Contract”: http://enr.construction.com/news/transportation/archives/080404.asp

62 IHC Merwede: “Dredging Towards the Centenary of the Panama Canal”: http://www.ihcmerwede.com/about-ihc-merwede/news/newsmessage/article/cooperation-agreement-for-ihc-backhoe-dredgers-between-ihc-merwede-and-liebherr-france