"It is important for contractors to dispose of fill carefully and legally. Council is concerned about illegal dumping because the contaminants can cause serious harm to the environment and to human health.
"Our scientists report that it causes discharges to the environment of heavy metals including lead, other metals such as arsenic, petroleum products and harmful chemicals such as cyanide.
"Illegal dumping can also result in uncontrolled discharges of sediment to our waterways and the sea causing harm to fish and other aquatic life, and to vegetation. Sediment is the largest cause of shellfish loss in our marine environment," said Ms Harris.
Mike Adams, managing director of Adams Landscapes, said his company was being made a scapegoat.
"It was only one load. This was a definite mistake, but the council were out to make an example of us," he said.