MONITORING THE DISPOSAL OF COAL FLY-ASH AT A DEEP-WATER SITE IN THE EASTERN MEDITERRANEAN-SEA

Coal fly ash (CFA) from the Hadera power plant, Israel, was dumped in the Mediterranean Sea some 70 km offshore, at a water depth of 1400 m. Using sonar equipment as well as water samples, it was found that the CFA descended to the bottom en mass at velocities ranging between 5 and 50 m min-1. A few hours after dumping, the water column was virtually free of CFA. Box core samples showed that the disposal site contained areas which were covered by a 0.5-1.0 cm thick layer of ash, determined both visually and by geochemical criteria (Al and Mn concentrations). CFA on the seabed ranged from clay to boulder-size particles. Comparison of the benthic fauna at the centre of the disposal site with that of a control area indicated a severe impoverishment of the benthos in the disposal area. The data obtained in this study on the disposal of CFA in the deep sea were compatible with the 'plop' model for dumped material and not compatible with a 'high dispersive' model.