5.1 Although the Convention contains no requirements
for provision of sampling points, the Guidelines for approval of ballast
water management systems (G8) adopted by resolution MEPC.174(58) do
expressly call for the provision of sampling facilities, not only
for the purpose of type approval, but also for the purpose of these
ballast water sampling Guidelines (refer to paragraphs 3.2, 3.8, and
section 8 of the Guidelines for approval of ballast water management
systems (G8) for further detail regarding provision of sampling facilities).
5.2 Samples should be taken from the discharge
line, as near to the point of discharge as practicable, during ballast
water discharge whenever possible.
5.3 In cases where the ballast system design does
not enable sampling from the discharge line, other sampling arrangements
may be necessary. Sampling via manholes, sounding pipes, or air pipes
is not the preferred approach for assessing compliance with regulation
D-2. Scientific trials have shown that using these sampling locations
may not provide accurate estimates of organism concentrations that
would occur in the discharge, i.e. such sampling may provide an under-
or over-estimate of the concentration of organisms.
5.4 In-tank sampling should only be used if ballast
water treatment occurs on uptake prior to or whilst ballast water
is in the tank. If any part of the treatment process occurs during
the ballast water discharge, then in-tank sampling will be inappropriate.
5.5 In light of these potential shortcomings,
sampling to determine compliance with regulation D-2 should, whenever
practicable to do so, be carried out in the discharge line near the
discharge point.
5.6 An exception to this is the case when tanks
are emptied through direct overboard discharge valves, as in upper
side wing tanks, rather than through the ballast pumps. In such cases,
tank sampling may be an appropriate approach.