Ballast Water Sampling and Sample Analysis for Compliance Control - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 173

In contrast, compliance control for the D-2 standard, which is a numerical, biological,
discharge standard, samples should be taken from the ballast water discharge line
(but see below). Here, a quantitative biological approach is needed as the numerical
standard refers to viable organisms above 10

m in minimum dimension no matter
what type they are. In contrast, for the indicator microbes as stated in the D-2 stan-
dard, both qualitative and quantitative approaches are needed so that the concentra-
tion of colony forming units of certain indicator microbes can be documented.
Although it seems that in-line sampling is the most appropriate way to assess com-
pliance with the D-2 standard, this view changes in cases when the ballast water
originates from a high risk area, i.e., an area with a known occurrence of target
species. In these situations samples may preferably be taken from the ballast tank
prior discharge, which would make non-compliance actions possible before the
water is discharged into the recipient environment. The in-tank approach is also
advisable for D-2 standard compliance checks for those tanks which have direct
discharge to sea, e.g., top-side tanks on some bulk carriers.

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Tank Selection - Which Tank to Sample (First)?

Vessels may have ballast water on board to be discharged which originates from
different sources and also with different uptake dates (holding time on board).
Ballast water from all different sources might need to be tested. If this is impossible
or in cases of a need to have results as soon as possible, possibly even prior any
discharge, tank(s) to be sampled fi rst should be selected based on a risk assessment
approach. This risk assessment will focus to identify which ballast water may con-
tain potentially harmful species for the recipient port.
Such a risk assessment may consider the following elements, but may not be
limited to:

• the environmental compatibility of both, the ballast water source area and the
ballast water recipient area;
• the presence of harmful aquatic organisms and pathogens (HAOP) in the area of
ballast water origin;
• if appropriate, the presence of target species in the area of ballast water
origin; and

• the duration of the in-tank holding time.

The tank(s) with higher environmental compatibility of the origin and discharge
area, tank(s) fi lled in a ballast water origin area where HAOP or target species are pres-
ent, and tank(s) with shorter in-tank holding time should be given priority for ballast
water sampling because these would likely pose the highest risk to introduce HAOP.
When in-tank sampling methods are applied, the ease of the sampling access
point may be used as an additional criterion to identify the tank(s) to be sampled,
also considering that some tanks may not be accessible at all for in-tank sampling
(David and Perkovi

č 2004 ).