Ballast Water Sampling and Sample Analysis for Compliance Control - Global Maritime Transport and Ballast Water Management: Issues and Solutions - page 172

As part of the Port State Control efforts to demonstrate compliance with the
BWM Convention standards, port authorities may consider sampling of ballast
water for subsequent analyses. The ballast water sampling guidance approved by
IMO as the Guidelines G2 is mainly limited to general information. In this topic
chapter we focus on the selection of appropriate sampling methodologies to assess
compliance with the BWM Convention standards, i.e., the ballast water exchange
(Regulation D-1) and performance (Regulation D-2) standards.
If the sampling event has to demonstrate D-2 standard compliance, then a numer-
ical documentation of viable organisms greater than or equal to 50

m in minimum
dimension is especially challenging because only less than 10 viable organisms per
1 m 3 of water are acceptable in the discharged ballast water. It becomes obvious that
various diffi culties can occur including to collect more than 1,000 l of water to proof
compliance, and several replicates may have to be sampled to meet general scien-
tifi c standards and accuracy levels. Further, the accuracy of the sampling technique
used must be validated because ineffi cient sampling techniques may result in inap-
propriate results.
Different vessel specifi cs, considering vessel types, sizes and cargo profi les,
result in very different ballast water discharge profi les and times. Ballast water may
be discharged “at once” or “in sequences” which may last from approximately 1 h,
e.g., emptying of two tanks in parallel on a container vessel, up to several days for
larger bulk carriers or tankers. The tank discharge duration is also depending on the
length of the cargo operation, e.g., tankers, bulk carriers, very large container ves-
sels, and sometimes also general cargo vessels, load cargo over up to several days
duration. Therefore, the ballast water operation is frequently conducted in sequences
over time until the cargo operation is completed. This factor is important to be con-
sidered when planning a sampling event as it is diffi cult to assume that the PSC
offi cer and/or sampling team will stay on board a vessel for several days.

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Sampling Methods According to the Sampling Access Point

Ballast water sampling access points may be divided into in-tank and in-line
(at discharge) sampling points. In-tank sampling points enable ballast water access
directly from a tank and this may be achieved either via opened ballast tank man-
holes, sounding or air pipes. In-line sampling points are located in the ship's pipe
work, preferably after the ships ballast water pumps.
For D-1 standard compliance monitoring in-tank or in-line samples may be taken
to either proof the presence of coastal biota or for water salinity checks. This may be
done by utilizing all possible sampling access points including sounding pipe, man-
hole and the vessels main ballast water line. However, the latter is not recommended
to be used because a discharge to sea may most likely occur in this sampling approach
and in case of non-compliance the non-complaint water would be pumped into the
recipient environment during the sampling event. As the D-1 standard is not a numer-
ical organism standard quantitative biological sampling is not needed.