Jip 4 At-sea monitoring of surface dispersant effectiveness

example of the equipment and related procedures required for a field effectiveness test is the

Australian National Plan Oil Spill Dispersant Effectiveness Field Test Kit (Nat-DET) Operational Guide,

available at: 

http://www.amsa.gov.au/forms-and-publications/Publications/NatDET_Guide_2012.pdf

.

SMART protocol

The SMART (Special Monitoring of Applied Response Technologies) protocol was developed by

the U.S. Coast Guard (USCG) and others. SMART has three tiers (note that these are not related

to the response tiers used in contingency planning):

l

Tier I: visual monitoring.

l

Tier II: combines visual monitoring with on-water teams conducting real-time water column

monitoring (using a fluorometer) at a single depth with water sample collection for later analysis.

l

Tier III: expands on the Tier II water monitoring to meet the information needs of the incident.

This may include monitoring at multiple depths (using the fluorometer) and also taking water

quality measurements or more extensive water samples.

The initial motivation behind the development of

the SMART programme was to provide the spill

incident Command with technically valid

information on dispersant application. This

protocol was to be used for guidance only to

confirm that dispersant application was working.

The SMART protocol seeks to strike a balance

between the operational imperatives in quickly

obtaining data while still following sound scientific

principles. The SMART Protocol does not attempt

to produce an oil mass balance but rather infers

and provides an indication of the relative

effectiveness of the dispersant.

IPIECA-IOGP Oil Spill Response Joint Industry Project

10

Successful dispersion of

weathered oils is possible

under some

circumstances. The

picture shows Alaskan

North Slope crude oil

being dispersed during a

sea trial after 55 hours

weathering and a viscosity

of 15,000–20,000 cP; the

dispersed oil cloud can be

clearly seen.

Tier I: visual monitoring

Tier 1 recommends the use of either trained or experienced persons to observe the development

of a light-brown coloured cloud or plume of oil, which is used as an indicator to determine that

the dispersant is working. These visual observations can then be augmented by remote sensing

technology, such as IR detectors, if available. The methodology and training for such visual

observers has been well developed in the addenda to the SMART documentation. In some

circumstances it can take tens of minutes for the dispersion to occur, and observers should take

this into account if rapid dispersion is not observed. 

Sour

ce: Dr T

im Lunel, ITOPF

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It is important to note that false indications can be observed which

may lead to inaccurate conclusions about the effectiveness of the

dispersant. Oil ‘herding’, for example, occurs when the oil is not

treated by the dispersant but instead is displaced by the dispersant

application platform or dispersant spray; on a smaller scale, this

phenomenon is known as ‘lacing’. Herding and lacing give the

appearance that the dispersant was effective, even though little

dispersion has actually occurred. Conversely, during application, it

is also possible that the dispersed oil can be hidden under any

remaining surface oil, giving the impression that the dispersant was

not effective. If the dosage rate was too low, or the oil was not

particularly amenable to the application of dispersant, a visual

observation may lead to the conclusion that it was not effective. In this scenario, it would be more

accurate to conclude that a higher dose rate or second pass is required.

A milky white plume in the water will be present if the dispersant has missed the oil or has run off

extremely viscous or highly emulsified oil.

Visual monitoring requires good viewing conditions. Some weather conditions, such as fog and

haze, will make it difficult to carry out any observations of slick behaviour, including in particular

efforts to identify a cloud of dispersed oil.

Tier II: on-water monitoring

The Tier II protocol was developed to provide more reliable data, and involves the detection and

sampling of the underwater cloud or plume using either water column sampling for subsequent

testing, or in-water monitoring using fluorometry. Either sampling method will produce a single line

data set at the depth at which the sampling occurs. It is recommended that this depth is 1 metre

but in rougher weather conditions it may be more suitable to deploy at a depth of 2 metres.

Sampling and fluorometry readings should be taken where:

i.

no oil is present on the sea surface (background);

ii.

oil is present on the sea surface (natural dispersion); and

iii. oil has recently been sprayed with dispersant (chemically dispersed).

A transect should be followed through the slick when taking the fluorometry readings, as

illustrated in Figure 3 on page 12. The protocol suggests a rule of thumb, i.e. that if there is an

increase in readings of five times between the untreated oil (left) and the dispersed oil (right), the

dispersant may be considered to be effective.

The use of Tier II (and Tier III) monitoring is most readily carried out when dispersant is applied

from vessels. Although airborne application of dispersant can be extremely effective, post-spill

monitoring following an aerial spray operation can be challenging. To accurately deploy a

monitoring vessel into a zone that has been sprayed from the air needs well-practised teams that

routinely perform exercises in conjunction with spray aircraft. Although post-spill monitoring may

11

At-sea monitoring of surface dispersant effectiveness

Natuna Sea, Singapore,

2000: a white plume

indicates that the

dispersant is not effective

on this highly viscous oil.

Sour

ce: Dr T

im Lunel, ITOPF

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