Prestige: Use of beach cleaners in Aquitaine
Unlike the Erika spill which impacted a very rocky coastline involving beaches followed by rocky stretches, the oil from the Prestige beached on endless stretches of sandy beaches. Organising efficient manual response was seriously hampered by the stretches of sandy beaches, the fact that access to them was far from easy and tides that did not help either. The situation would have required either tens of thousands of responders who wouldn’t have had all that much to do or else organise an enormous transport effort from one work site to another every day to contend with the recovered quantities.
The fact is that the oil would tend to be remobilised constantly by the wind, waves, tides and currents and require constant reorganisation from the logistics point of view. Wind and wave action was such that responders were prevented from cleaning up the oil two hours before and after high tide. Repeated beachings of oil coupled with the constant threat from offshore of more slicks to come forced responders to focus on removing the bulk of the oil whilst fine tuning was left for much later on.
In view of this, plus the fact that the public and local politicians just did not want to see responders keep on using the bucket and spade technique, the Polmar authorities decided to use machines as often as possible and indeed requisite numbers of men and machines were put to work on these beaches.
Manpower
Rapid
mobilisation of professionals from the ministries, the Civil Defence
Corps and private companies that were requisitioned was an efficient
way of boosting the work already being done by the local authority
personnel without having to call in endless numbers of voluntary
workers. As of the month of April private companies were doing the
job to take over from the professionals after securing contracts
for this purpose.
Oleophilic rolls
These
are rolls covered with oleophilic material or easy to replace geotextile
connected to nets and were used down by the water’s edge or
low tide mark on newly beached oil to prevent it from mixing with
the sand or being remobilised by the waves. Two types were used:
large size and small size rolls. The large ones were pushed by tractors
and were 4 metres long. The small ones were pulled by quads or tracked
vehicles in swath widths of 1.2 metres to treat dispersed or concentrated
oil at the water’s edge.
Small drum pushed by hand operated caterpillar,
in Lège (33), Jan. 2003. (Source: Cedre)
Beach cleaners
Using non self-propelled beach cleaners on
beaches in Gironde (33), Jan. 2003. (Source: Cedre)
Standard
beach cleaners were used widely during the Erika response operation
and were also very useful for use on the Prestige spill where in-depth
cleaning was not required (they were used at the top end of the
foreshore or at the foot of the dunes). Every single available machine
was mobilised and provided good results providing that the drivers
were suitably trained and watchful in terms of selectivity (fine
adjustment of the blade, vibration rate of the mesh screen, speed
and tyre pressures).
Small size beach cleaners
These
machines also turned out to be effective on the Erika spill and
proved to be invaluable on seepages of oil at the foot of the dunes
(fragmented tarballs). The use of fine mesh screens and multiple
passes improved selectivity and kept sand removal to a minimum whereas
with bigger machines selectivity is usually very low. With micro
tarballs and standard tarballs, these machines proved their superiority
over manual collection and tractor-driven beach cleaners. The small
size beach cleaners were used mainly for fine tuning amenity areas
used by tourists in summer.
Hand operated beach cleaner being used in Lège
(33), Jan. 2003.
Manual collection
Manual collection is very often regarded as generating high cost/low performance results but when combined with beach cleaners, manual collection:
- can involve raking the sand in front of the machines to lower the number of passes, improve encounter rates and mitigate burying caused by multiple passes
- can involve raking slopes where tractors cannot go
- can promote selective collection (with less sand) of the pollutant in small, lightly oiled areas that are either inaccessible or covered by vegetation
- can help sorting procedures when too much beach material has been collected and the authorities need to optimise the treatment chain for collected waste.
Manual
collection was seen as an adjunct to using machines but nevertheless
required the right kind of adaptable equipment. Responders would
usually take a range of such equipment with them in the service
vehicles, e.g. pointed sticks for viscous pellets and cakes, rakes
and scrapers for dry dispersed oil and gridded spades for emulsioned
pellets and cakes.
Surf washing
Surfwashing (64), April 2003. (Source: Cedre)
This
technique involves pushing oiled sand down to the water’s
edge where it will be mixed by wave action and was used extensively
on many beaches in the Landes and western Pyrenees but only after
consulting with geologists and geomorphologists and conducting a
prior assessment for each selected site where surf washing was being
envisaged. These sites were monitored very closely. Once the wave
action had separated the sand from the oil, the oil was collected
using mats and nets and oleophilic rolls or even manually if the
oil stayed at the water’s edge.
Beach cleaner collection bucket, in Lège,
May 2003. (Source: Cedre)
Last update: April 2004