dumping in Castle Harbour.

Chief Engineer Mr. Neal Allen said a new concrete-making plant by the incinerator has been taking incinerator ash and mixing it with concrete and water to concoct the correct `recipe' for the best mix for the blocks.

"For the last couple of weeks, the plant has been tested to make sure it is working,'' he said.

"We have made about 100 blocks, but the main concentration has been that of the mix design itself.'' Mr. Allen said the plant has been trying several "recipes'' to fit rigid standards required by SAL Limited, which has been contracted to make and set the blocks for landfill around the Civil Air Terminal.

The blocks are made from ash removed from the incinerator's pit. Lumps larger than four inches in diameter are sifted out with the remainder sent by conveyor belt to a magnetic separator. In a similar process to that used for ready-mix concrete, the ash powder is then weighed and mixed with cement.

Water is added according to the amount of moisture already in the ash. The resulting mixture is put in a ready-mix truck and taken to the Airport to be placed in three-foot by three-foot moulds. About two days are required to give the mixture time to harden.

The blocks are then removed and allowed to stand for a day or two to build the strength of the blocks.

Mr. Allen said the blocks currently being made will be placed into the ocean around the dump at the Airport to form a breakwater. They will also become a barrier to keep items such as refrigerators and crushed cars from floating to sea.

It is also hoped the blocks will form a lagoon around the area.

The ash block plan was approved by the Development Applications Board over protests by environmentalists who feared the blocks would leach toxic elements into the water.

A 1993 report by the Water Quality Institute in Denmark concluded that the safest option for ash disposal would be to form blocks.

But it said the safest place for dumping was off Tynes Bay itself. The airport was considered the second-best dumping option.

BLOCK PARTY -- Recently made up with ash from the Tynes Bay incinerator, these concrete blocks are being put into the water around the Airport dump area to provide a breakwater. Pictured from left are: Correia Construction workers Mr.

Charles Peniston and Mr. Joe Correia, and bystander Mr. Howard Johnson.