The Erika spilled a very high density, high PAH content persistent heavy fuel oil that impacted over 400 kms of France's West Brittany coastline resulting in a protracted period of shoreline cleanup. One of the sites oiled by the HFO was Pen Bron, located seaward of the Croisic salt marshes. This laarge and very environmentally sensitive area with extensive salt pans and bivalve production was polluted by a significant spill of sunken oil buried in the sediment. In view of the risk to local resources and amenities, operations were undertaken to remedy the sunken oil spill: the pollution was mapped and cleanup techniques studied to define the optimum technique for removing the oil that sank and was buried in an area subject to strong tidal currents. Site restoration was conducted in two stages:

  1. Sediment in the most polluted area (700 m2) was mobilized by a mechanical shovel dredge mounted on a barge and the sediment was sent to a refinery to be disposed of along with waste from other locations.

  2. Sediment from the surrounding area (10 000 m2) was removed by a pump dredger; pumping the sediment - oil - water mixture ashore to a lagoon where the oil was removed from the sediment by floatation and skimmed while the water was filtered before being released. The residual oil concentration in the sand was monitored by chemical analysis to decide on how to dispose of it best: replacing it on site or treating it as a specific waste.

This operation involved over 5,500 tonnes of sediment. Environmental impact was minimised as 85% of the sediment was reinstated safely on site, thus avoiding the risk of shoreline erosion which could have happened in the event of excessive sediment removal.

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