ABSTRACT
On January 31, 1988, the Amazzone spilled about 1,500 tons of a highly paraffinic medium fuel oil (having a pour point of 36°C) along a distance of 300 km off the coast of Brittany. Due to very rough sea conditions, no offshore recovery operation could be carried out. Most of the pollution was beached as scattered patches on numerous sites, including pebble beaches in south Finistère, which had been especially difficult to clean during previous spills.
In this area, the pebble banks that protect the dunes are relatively exposed to erosion. It was therefore decided to try cleaning these pebbles on site using the mobile plant that was designed for washing polluted sands and tested in 1985.
The plant prototype was put in working order and conveyed to the site on the Baie d'Audierne. The equipment was very easily adapted to washing the pebbles polluted by a mixture of sand and fuel oil emulsion. A total of 1,400 m3 was cleaned during 10 days at the end of March. The plant worked smoothly with a load of 20 to 25 m3 of pebbles per hour and using a petroleum solvent as a washing agent. Because the ambient temperature was rather low (around 5°C), cleaning was performed with warmed water.
Compared to other techniques that could be used to clean polluted pebble beaches, the washing plant proved very effective (providing good cleaning and high throughput) and competitive (costing less than quicklime treatment, for instance). Another advantage of this technique is that cleaned pebbles are returned to the beach, helping the pebble bank to keep its anti-erosion function.
