MACKAY EQUALS WORLDS WORST ACID SULFATE SOILS

A few weeks ago, The Great Barrier Reef Marine Park Authority organised Associate Professor Paul Saffigna, Foundation Head Graduate School of Environmental Sciences and Engineering at Griffith University and a scientist, Sheridan Morris, to tour the Mackay area. Associate Professor Scaffigno who is a world renowned expert in rehabilitation of problem soils, particularly Acid Sulfate Soils, gave a public lecture on the dangers of Acid Sulfate Soil and the need for their reclamation.

Acid Sulfate Soil contamination has caused major problems in both northern NSW and southern Queensland. In some extreme cases, concrete foundations, in such building constructions as houses and bridges, have failed as the acid has "eaten out" the calcium in the concrete. Some buildings have prematurely deteriorated with builders unfairly blamed for poor workmanship.

Both Associate Professor Saffigna and Sheridan visited some of the problem areas of Acid Sulfate Soil contamination in Mackay. The worst example was a drain approximately half a kilometre long, 10 metres wide and 2 metres deep constructed by Mackay City Council to drain a Melaleuca swamp at the rear of the Bucasia Sewerage Treatment Plant. The drain empties directly into the Reliance Creek Fish Habitat Reserve.

Spoil material and the sides of the drain were tested in the field for Acid Sulfate Soil Potential. Some of the exposed spoil material showed a pH as low as 0.9, which Professor suggested was extremely toxic. The professor was surprised by how bad the toxicity level was and he stated that it was amongst the worst levels that he had encountered anywhere in the world. The meter used to test these values was rechecked for accuracy to double check the readings at the insistence of the Professor. The meter was proven to be reading correctly.

Both scientists expressed extreme concern for the toxic effect of any run-off from this drain into the nearby marine environment if it was not treated correctly and urgently.

"If this is allowed to enter Reliance creek without such proper treatment, then major loss of marine life and possible fish kills on a large scale would probably result", the Professor said.

Both scientists strongly urged that extensive testing for Acid Sulfate Soil of all areas in Mackay and district be undertaken as a matter of urgency before any developments of these areas occur. This is especially important in all areas below 5 m AHD, in Mangrove and all Wetland areas including Melaleuca forests because of the very serious nature of the problem in this area.

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