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Article paru dans Watertown Daily Times : Checking ballast water fairly simple
Le 27 mai 2008
SALINITY TESTS: Seaway scientist boards ships near Montreal to ensure saltwater flushing has been done
MONTREAL - Determining the salinity level of water in the 16 ballast tanks of a 600-foot oceangoing cargo ship seems like a monumental task. But in reality it's not unlike, and almost as easy as, checking the engine oil in a Buick.
Almost.
Under regulations adopted in March by the American and Canadian managers of the St. Lawrence Seaway, all vessels entering the Great Lakes must flush their ballast tanks with salt water at least 200 nautical miles offshore. Research has proven this practice to successfully kill most potential invasive aquatic species.
And because it guards the entrance to the St. Lawrence Seaway, the only water route into or out of the Great Lakes, the St. Lambert Lock in Montreal offers a perfect inspection site.
"This is the place that we need to exercise the judgment and the authority to provide the protection the Great Lakes deserve," said Collister "Terry" Johnson Jr., administrator of the St. Lawrence Seaway Development Corp., which oversees Seaway operations in American waters. "We now know from research and science that salt water is a very effective killer of freshwater organisms."
On May 5, Terry Jordan, a Seaway Development Corp. marine specialist, boarded the cargo ship M/V Federal Kivalina to inspect the ballast water in its 16 tanks. Because the ship was laden with cargo, all pumpable ballast had been removed from the tanks, leaving 2 to 6 inches of residual water and sediment at the bottom of each one. Fully loaded, the ship's tanks can hold a combined 12,000 cubic meters of ballast water. In either case, the new regulations required a full inspection.
On deck, Mr. Jordan met with the ship's bosun, Mohammed Sanghri, who is in charge of the deck crew, to perform the inspection.
"We still want to make sure that if they're doing cargo operations and taking ballast in the Great Lakes that there is ocean salt water in those tanks," Mr. Jordan said.
Mr. Sanghri uncapped a slender tube, called a sounding pipe, protruding from the tank up through the deck. He then inserted a metal weight attached to a tape-measure-like device, which he unwound for 45 meters until it reached the bottom of the tank. He then rewound the tape, pulling the water-soaked weight from the tube.
Mr. Jordan took the weight and dribbled a few drops of water onto the lens of his refractor, a tubular, kaleidoscope-like device. With an eyepiece on one end and a prism on the other, the refractor is used to measure the salt content of a water sample. The prism bends light through the sample, where the dissolved salts within refract, or scatter, the light, sending a shadow across the instrument's salinity scale. The salinity reading is taken at the point where the shadow crosses the scale.
To pass the inspection, the ballast water must contain salinity of at least 30 parts per thousand. The process is repeated at each ballast tank. Each time, the weight is dried and the refractor is cleaned and recalibrated to zero.
Of course, accompanying any inspection regime is a paper trail to document the results. Inspectors also must check the vessel's documentation to verify compliance with the new regulations.
In Federal Kivalina's control room, Capt. Harish Matta showed the inspectors the ship's ballast logs, which document the dates, times and locations of offshore ballast water exchanges. He also presented ocean charts marked with the same information, along with the ship's ballast water management plan.
Mr. Jordan, who has been testing ballast water since 1990, said this last document is crucial because different countries have different standards for dealing with ballast. He said Australia, Japan and Korea are the most stringent.
"Ballast water plans must comply with location to which [the vessel is] going," Mr. Jordan said. "Everybody has their own regulations. And it's up to the ship and the owners to understand and know the regulations. Inspectors look at ballast management plans to make sure the vessel has a plan to deal with ballast in the Great Lakes."
The Federal Kivalina passed its inspection and was given the go-ahead to sail to Ohio, where it would offload more than 28,000 metric tons of synthetic rutile sand, a component in the production of titanium oxide.
Mr. Jordan said a typical inspection takes 45 to 90 minutes, depending upon the number of ballast tanks onboard, ease of access to the sounding pipes and even the weather.
So far, he said, compliance has been good: "All vessels have complied with the regulations and there hasn't been any unmanaged ballast going through."
Coming up:
Part 3: The science of fighting invasive species and what the future holds.
