Environmental Engineering Reference
In-Depth Information
In practice this implies diffi culties especially for the designation of BWEA in
shallow seas (e.g., North Sea, Baltic Sea) or semi-enclosed seas (e.g., Adriatic).
Considerations should be given to the trade-offs between (a) additional ballast water
discharges in such areas, (b) the dimension of the BWEA to allow complete BWE
and (c) to its location to avoid major deviations from the vessels' intended routes. To
meet the requirements vessels with bigger ballast water capacities may slow down
when sailing through BWEA to gather extra time to complete the BWE operation or
to exchange just the “critical” (i.e., assessed as highest risk ballast) ballast water. A
decision on the minimum management measure required should be taken according
to the level of RA (see chapter Risk Assessment in Ballast Water Management ).
BWEA should be biologically monitored frequently to document the presence/
absence of introduced species or other HAOP. A worst case scenario may be that
HAOP become introduced and established in such an area and are rapidly spread
unnoticed due to the ongoing BWE activities in this area.
A unique situation occurs in e.g. Europe and USA as some of the busiest ports are
located in estuaries with brackish or even freshwater conditions (e.g., Antwerp,
Hamburg and parts of Rotterdam, inner parts of Chesapeake Bay and San Francisco
Bay). A high risk for a species introduction occurs when freshwater organisms (e.g., the
zebra mussel) are transported in ballast tanks between two freshwater ports, but these
two ports are separated by marine water conditions, which poses a natural migration
barrier so that the freshwater organisms cannot spread by their natural means between
these freshwater ports. In those instances BWE in higher saline waters, also in coastal
waters (i.e., <50 NM from the nearest land and <200 m depth), may be a risk reducing
measure. However, some organisms show a very wide salinity tolerance, i.e., BWE
alone will not completely eliminate the risk of species introductions.
We therefore recommend that freshwater ballast should be exchanged in
marine waters even if this is in coastal waters provided that the voyage is suffi -
ciently long to complete BWE en-route in marine waters for the ballast water
intended for discharge.
Undue Delay and Deviation from Planned Route
As per the BWM Convention vessels should not be forced to deviate or be unduly
delayed by BWM requirements. The BWM Convention gives the vessel a right for
compensation when it has been unduly delayed. However, the term “undue delay”
has never clearly been defi ned by IMO in relation to the BWM Convention or other
IMO applications.
The designation of BWEA should not require major vessel deviations. However,
a cost/benefi t analysis considering the costs caused by negative impacts of introduced
species vs. re-routing costs for shipping may reveal that a slight re-routing of ves-
sels may be considered. Similarly, if a RA identifi es that a vessel carries ballast
water with an unacceptable risk, then the reasoning for a deviation may apply and it
is therefore not “undue”. It may therefore be considered that vessels use specifi c
routes even if this results in a delay of a few hours.
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