CONTROL OPTIONS

The committee considered the possibility of the concurrent development of a plan for loading and discharging ballast water and the ship cargo plan. For example, if a ship is to load bulk cargo of various grades, or different bulk cargoes in different ports, it would be useful to develop an associated ballast water operations plan, taking account of information on locations and times when ballast is likely to contain unwanted organisms (see above). In this way, the master could adjust the requirements for loading and discharging ballast. Even though the plan for managing ballast could be as complicated as the typical cargo plan, this method would provide flexibility in planning for contingencies.5 The committee agreed that a plan for managing ballast water should be mandatory when target organisms, such as those from global hot spots, are involved.

The various options described earlier complement the plan for managing ballast water because they give the ship operator more flexibility for planning for each voyage and each port of call on a case-by-case basis. To take maximum advantage of this approach, educational and operational guidelines that address each option would be beneficial. In some cases, specific operational procedures would have to be approved in advance by the ships' classification society or flag state administration.

Some specific examples of control options for managing ballast water that may minimize or prevent the unintentional introduction of nonindigenous aquatic nuisance organisms are given below:

  • Change ballast water at sea with engine cooling water heated to a temperature in excess of 45°C (110°F).6 Research has shown that cooling water heated to this temperature is completely free of live microplankton (AQIS, 1993). This is not necessarily an option for treating all the ballast water on board for all micro-organisms or for dealing with large quantities of ballast water. (Onboard thermal treatment is discussed in Chapter 4.)

  • Take ballast water on board using high-ballast-water suction if unwanted organisms are known to exist in the bottom sediment. Alternatively, the ship could partially ballast at the cargo discharge berth and finish ballasting upon departure but while still in calm waters.

  • Prohibit deballasting in U.S. waters by ships on some voyages when ballast water can be retained on board. Some container ships have computerized plans for discharging ballast water. With careful preplanning, these ships could dispense with discharging ballast in U.S. ports. In other circumstances, ships engaged in liner/break-bulk cargo trades may have enough ballast water tanks to keep ballast water on board during a roundtrip voyage. For example, the ship's ballast water intake can be planned such that alternate ballast tanks are used to carry water picked up in a given U.S. port of discharge later into the same port area.

5  

6  

 Most ships currently plan ballast loading and discharge based on ship strength and stability, without consideration of possible introductions of nonindigenous species.

The quantity of heated cooling water on board a ship is directly related to the horsepower of the main engine.



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