Ambès: Pollution response operations
On 12 January at 10:30 a.m., Cedre was informed of the accident by the Bordeaux port authorities. Cedre was subsequently contacted by Total (shareholder of the operator SPBA), then by the local authorities of the Gironde area, who reported a spill of 50 m3 into the Garonne. Two members of Cedre’s response team were mobilised. They arrived at the depot on 13 January 2007. Cedre’s onsite intervention was mainly based on the protection of the aquatic environment (rivers and channels) and later on their clean-up. The FOST (Fast Oil Spill Team: stockpile of equipment belonging to TOTAL and operated by the personnel of the military fire brigade of Marseille) was also mobilised.
Daily aerial, nautical and on foot reconnaissance surveys were organised on the first five days. These surveys helped to assess the situation (50 m3 of oil drifting and 40 km of soiled banks) and to define intervention strategies on the Garonne, Dordogne and the Gironde rivers. The priority was to stop the pollutant from leaving the site.
From 12 January, major pumping operations were conducted on the main road, in the trenches and in the drainage ditches. The rainwater drainage ditches were plugged with earth. Meanwhile, dispersants were applied. The river traffic was temporarily interrupted, but resumed later the same day to promote mixing of the oil in the water column.
The buoy tender the Gascogne, equipped with a weir skimmer and an “Aristock” tank, was mobilised but experienced difficulties in recovering the oil due to the heavy currents and extensive spreading of the oil.
Sorbent booms were set up by coastal pilots around all the wharfs in the area to trap floating pollutant. The FOST also deployed sorbent booms, as well as a shore-sealing boom, and later a makeshift boom, in front of the rainwater outlets from which oil was being discharged.
The oil recovery unit Piranha, a boat able to navigate in very shallow waters, arrived onsite. It was equipped with side nets designed to recover floating waste in the Mediterranean ports. The Piranha began the dynamic recovery of trails of pollutant and floating waste. Its efficiency was later improved by filling the bottom of the nets with sorbents.
On 19 January, a decision was made to build cofferdams on the banks of the Garonne using a power shovel at all the rainwater outlets in line with the site. These structures were constructed in order to create a trench where the oil would accumulate, under constant monitoring, and then be pumped out when necessary. These constructions were rebuilt after every spring tide which weakened them.
On 20 January, the company Atlantique Haute Pression (AHP), specialised in pressure washing, mobilised by the site operator, began initial clean-up of the banks, which involved the collection of patches and patties, both clean and oiled waste, to prevent clean waste from being subsequently oiled.
The monitoring and maintenance of the sorbents (used to recover the pollutant rinsed from the banks by the river) in line with the site by the Pirahna and FOST, the collection of residual floating pollutant by the Pirahna and clean-up on the banks by AHP continued until 25 January.
Operations came to a halt at this point due to the snow and then the weekend. FOST was demobilised on 26 January. The operations recommenced on 29 January, and came to an end on 31 January for the clean-up of the banks and 7 February for the monitoring and maintenance of the sorbents by the Pirahna.
It was not thought necessary to conduct final clean-up operations on the banks of the Garonne, as these areas were difficult to access, dangerous, sensitive to excessive trampling and subject to a high level of natural clean-up by the river. Furthermore, nautical reconnaissance carried out by Cedre on 13 and 24 January showed rapid rinsing of oiled vegetation: the 10 km the least affected had been naturally cleaned by 24 January.
The reconnaissance survey conducted on 6 March showed that only 10 km were still polluted and that the vegetation had begun to grow back on the banks. On 5 April, surveying showed that the stretch still polluted had reduced to 3 km on the right bank of the Garonne. A final reconnaissance survey on 3 July 2007 reported only three small clusters of oiled vegetation in front of the depot.
During winter 2007-2008, the marshland trenches were under permanent surveillance and no deterioration in the situation was reported. In February 2008, all the water samples collected tested negative for hydrocarbons. Soil samples were tested in September 2008 and the results confirmed the natural extenuation of the residual pollution previously reported by Cedre's laboratory. Weekly monitoring was nonetheless conducted throughout the summer to reassure all parties. Following a final visit, organised on 18 September, the permanent monitoring arrangement was able to be lifted.