Environmental Engineering Reference
In-Depth Information
Indicative Sampling for Compliance Control
with the D-2 Standard
The indicative sample analysis is addressed in the Guidelines G2. Paragraph 6.3
reads: “Prior to testing for compliance with the D-2 standard, it is recommended
that, as a fi rst step, an indicative analysis of ballast water discharge may be under-
taken to establish whether a ship is potentially compliant or non-compliant. Such a
test could help the Party identify immediate mitigation measures, within their exist-
ing powers, to avoid any additional impact from a possible non-compliant ballast
water discharge from the ship.”
For ballast water sample analyses, certainly, as a very fi rst step, a sampling event
needs to be performed, but Guidelines G2 do not address explicitly how an indica-
tive sampling event would need to be conducted. Implicitly, an indicative analyses
could be performed with a sample, or a part of it, which was taken during the
detailed D-2 standard compliance control sampling process, or just on any stand-
alone sample.
One important point to note is that an indicative sampling event may be targeted
towards only one group of organisms addressed by the D-2 standard. The results
from each of these organism groups alone may already be taken as an indication that
a BWMS is not performing properly. From the author's experience of on-board type
approval sampling of BWMS, it is likely that, indicator microbes and organisms less
than 50
m in minimum
dimension meet the D-2 standard, but it was observed that at the same time organ-
isms greater than or equal to 50
ʼ
m in minimum dimension and greater than or equal to 10
ʼ
m in minimum dimension may be found in too
high concentrations so that the acceptable organism numbers in the D-2 standard are
exceeded for this organism group.
Different groups of organisms in general require different sampling approaches.
In general organisms greater than or equal to 50
ʼ
m in minimum dimension require
larger water volumes to be sampled to collect them compared to organisms less than
50
ʼ
m in minimum
dimension. This is because there are usually lower concentrations of larger organ-
isms in the water as for smaller organisms. Consequently, indicative sampling meth-
ods may be very different for each organism group, and may differ in, e.g., sampling
duration, timing, volume, and further in the recommendation which sampling point
is to be used.
Without a known performance history of a certain BWMS it is very diffi cult to
predict in advance which group of organisms should be considered to identify pos-
sible non-compliance with the D-2 standard. Not knowing this in advance it would
be most effective to use a sampling method which enables an analyses of all organ-
ism groups. This would also enable a step-by-step process of consequtive analysis
methods. One analysis method for one organism group may be applied fi rst, and in
cases this shows an indication or even does not give an indication of non-
compliance, the second organism group may be tested next with another sample
analysis method.
ʼ
m in minimum dimension and greater than or equal to 10
ʼ
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