The Pacific Access Channel, shown here before flooding of its entrance channel was completed, is nearly done. When complete, the channel will connect to the new Pacific-side locks that are being built as part of the expansion of the Panama Canal. Courtesy of the Panama Canal Expansion Program
Phase three of dry excavation is complete on the Pacific Access Channel portion of the Panama Canal Expansion, a program that will double the canal’s capacity.
November 22, 2011--Last month, the Panama Canal Authority completed the third of four phases of dry excavation for the Pacific Access Channel, a 6.1 km channel that will connect a new set of three locks on the Pacific Ocean side of the Panama Canal to the Culebra Cut, a critical link to the canal’s Gatun Lake navigation channel. The $36-million third phase was completed on schedule, and work on the fourth and final phase of this critical portion of the project is halfway complete.
The third phase involved the excavation of 8.2 million m3 of materials; with the fourth phase half completed, approximately 35 million m3 of the total 50 million m3 of the material that is required to be excavated for the access channel has been removed.
When complete in 2014, the $5.25-billion Panama Canal Expansion Program will permit the movement through the canal of so-called “Post-Panamax” vessels—that is, those container ships, bulk carriers, and tankers that are larger than the maximum size that can currently traverse the canal. The expansion will double the canal’s capacity of 340 million tons per year. (Click here to go to the Panama Canal website.)
The expansion of the canal includes the Pacific side locks and another set on the Atlantic side at a total cost of $3.2 billion. There will also be a short 3 km access channel from the main entrance on the Atlantic side. The excavation for this access channel was actually begun by the United States in 1939, when it intended to build a third set of locks. The work was abandoned in 1942, when the United States entered World War II. The current work on this channel follows the same alignment and involves dredging rather than additional excavation because the previously excavated area has now been flooded to sea level.
Construction of the new Atlantic side lock has been advancing
steadily. The lock gate recesses, walls, culverts, conduits, and
utility crossings are being carved out from the sandstone prior
to the placement of concrete. Courtesy of the Panama Canal
Excavation of the Pacific Access Channel includes the leveling of Paraiso Hill, where the overall expansion project was begun, and the clearing of more than 400 ha of unexploded ordnance left behind by the U.S. military.
In addition to the new channels, both of the existing entrances to the canal are being dredged for navigational improvement. On the Pacific side, dredging involves the removal of hard material—namely, basalt, which makes up roughly 60 percent of the material—as well as some softer material. Dredging on both the Pacific and Atlantic sides is expected to be completed next year.
The Pacific entrance channel will be widened to 225 m and deepened to 15.5 m below the current water level. The dredging and dry excavation on the Pacific side will result in the removal of approximately 8.7 million m3
of material. On the Atlantic side, the existing entrance channel is being widened to 225 m and deepened to 16.1 m below the water levels. A north access channel leading to the new locks on the Atlantic side is also being widened to 218 m. The work on the Atlantic side includes dredging and dry excavation of approximately 17.9 million m3
The entrance to the Pacific Access Channel has now been
flooded, and the fourth phase of excavation is halfway done.
Courtesy of the Panama Canal Expansion Program
The new sets of locks will be 55 m wide, an increase over the width of the two existing lock sets on each side, which are 33.5 m wide. Each new lock will have three chambers, nine water-saving basins, and eight rolling gates. The water-saving basins will enable the new locks to use 7 percent less water per transit than the existing locks—and 60 percent of the lock water will be reused. The system will allow operators to fill each lock chamber in just 17 minutes.
This project also entails the removal of 28 million m3
of material to deepen and widen the Gatun Lake navigational channel and deepen the navigational channel at Culebra Cut.
“All projects are running well,” says Jorge Luis Quijano, the Panama Canal’s executive vice president of engineering. “The locks project is the most complex and expensive, and involves heavy construction.” (Click here
to view Webcam images of the expansion.)
Because the Atlantic side benefitted from the excavations already undertaken by the United States, dry excavation for the Atlantic locks will require less excavation—16 million m3
of material—than the 24 million m3
excavated on the Pacific side. To date, 20 million m3
of dry excavation has been performed. Dredging will bring the total amount of material removed to 53 million m3
Work on the Atlantic side includes dredging and dry excavation
of approximately 17.9 million m3 of material. Because sandstone
is prevalent, the work requires excavators but not explosives.
Courtesy of the Panama Canal Expansion Program
Blasting will be required only for the Pacific lock site. “On the Atlantic lock site, however, we have a sandstone-type material that is much easier to remove,” says Quijano. “Large excavators will do the job, [so] we don’t need explosives. On the Pacific side there is a layer of clay a few meters thick on top of hard basalt. Once the layer of clay is removed with excavators drilling and blasting follows to fracture the hard basalt.”
Contractors have installed industrial facilities to mix large amounts of concrete on-site at the locations of the new locks. The basalt removed from the Pacific excavation area is being crushed and used as rock and sand aggregate for both the Atlantic and Pacific construction sites; the crushed material is being barged to the Atlantic side for this purpose.
The concrete placements for the locks began last July at the floor slabs and culverts that will fill and spill both the locks. “The marine structures of the locks have stiff specifications with regard to intrusion of chlorides,” says Quijano. “We have specified the use of concrete with low permeability, so to achieve those levels you have to develop the right mixes that pass the different lab tests. It does take time to deliver the right concrete mix design. We have poured in the upper level and middle level in both locks.” While 90,000 m3
of the concrete has been placed already, Quijano says, “there is still a long way to go. We will use approximately four point eight million cubic meters for the whole project.” Quijano adds that at this time 2,000 m3
of concrete is the maximum being placed daily, but the project goal is to reach a daily and sustainable rate of 5,000 m3
The construction of the new set of locks on the Atlantic side is
advancing with the concrete placement of[ the upper chamber
walls and floor slabs. Courtesy of the Panama Canal Expansion
A high concentration of heavy steel rebar is being incorporated into the lock structures. In some cases, rebar up to size 14 is being installed to withstand the design seismic forces. “Trying to pour concrete around all of that rebar mesh is a considerable task,” notes Quijano. “There are many cutouts in the middle of the chamber for the culverts and conduits of the filling and emptying system, all requiring a high concentration of rebar installation. Over the last three months we have seen significant improvement and we expect to reach thirty thousand cubic meters per month production by November.”
The soil is largely uncontaminated and is being trucked or barged and deposited on designated disposal sites. The dry excavation projects require the proper disposal of the material in an arrangement that results in the creation of hills on the western bank of the canal. “They almost look like Mayan pyramids when they are done with the stabilization of the material in the disposal sites,” Quijano notes. Uncontaminated dredged material is also being barged and deposited to subaquatic areas offshore at distances up to 20 km away.
At Gatun Lake there is a 4 km section of reclaimed land near the Atlantic locks. “We feel we can make good use of the excavated soil being generated from the lock site on the Atlantic side to build a coastal band that faces Gatun Lake,” says Quijano. “The reclaimed land overlooks the lake and can be used for prime housing or a hotel complex that is near the new locks as well. We anticipate a good future in the use of this strip of water frontland.”
A smaller project will involve increasing the level of the Gatun Lake by 45 cm, which together with the deepening of the channels will provide additional storage capacity for more than 625 million liters of water in the lake—enough for three additional daily transits.
The canal—along with the contractors in charge of each component and in compliance with requirements of such institutions as Panama’s National Environmental Authority—is conducting wildlife rescue and relocation activities as work progresses in the different areas. Mammals, reptiles, and birds have been rescued and relocated to safe areas, while a reforestation project with native species is also being conducted.