Testbank/Sea Daniel

On 22 July 1980, the West German container ship Testbank collided with the Panamanian bulk carrier Sea Daniel in the Mississippi River Gulf Outlet (Louisiana). During this accident, 4 containers on Testbank were knocked overboard. They enclosed 3 steel barrels of hydrogen bromide and 16 tonnes of pentachlorophenol.

Shortly after the collision, a white haze of hydrogen bromide enveloped Testbank. The crew secured the ship's ventilation system and took shelter below decks. The white haze was carried by the winds into a village where 75 residents were evacuated from their homes.

A safety zone was established, closing the channel to all non-emergency traffic. An extensive search started for the sunk chemicals but the river water was muddy and the visibility very low. It was not until 8 days later that the search proved successful, thanks to a colour video fishfinder. Three barrels with hydrogen bromide were first very carefully salvaged and sealed in overpacks. The pentachlorophenol containers were found damaged and the pollutant scattered on the seabed. A grid was established by long piles driven into the bottom and rising above the water surface. Over 10 days approximately 90% of the pentachlorophenol was recovered by an air lift dredge, guided by the pile grid.

The dredged mud-water mixture was cleaned in a flocculation treatment barge and an active carbon filtration system. It was then analysed before being returned to the environment. In total, 1,100 tonnes of dewatered solid waste residue was packaged in fibre drums for transportation to disposal sites.

Sources:

• HELCOM, 2002, HELCOM Response Manual - Volume 2
• HOOKE, Norman, 1997, Maritime Casualties 1963-1996, second edition, LLP Limited, London