Asbestos- and lead-contaminated soil is being tipped illegally on random sites. Among new discoveries by the Department of Environment, Climate Change and Water is 1000 tonnes of sand containing asbestos fibre being spread across a soccer oval at Rockdale where children play.

The lure for criminals is the money - rogue operators avoid paying $3840 in fees to tip a truckload of waste at one of the state's 24 legal sites.

Department specialised regulation director Craig Lamberton told The Sun-Herald that investigators had conducted dawn raids across Sydney, seizing computers and records of businesses suspected of involvement in organised illegal dumping.

There was ''an underlying criminal element'' among the dumpers, he said, possibly because of the amount of money involved. Investigators had discovered that a number of operators illegally disposing of waste were involved in other criminal activities.

''There are some dumpers that are also known to be associated with bikie groups and in those cases we have to take police with us,'' Mr Lamberton said.

Some estimates put the amount of illegally dumped waste at up to 500,000 tonnes a year, legal operators say, but the department says it is hard to put a figure on it.

Industry members warn the department is not doing enough to stop rogue dumpers and had handed a ''shame file'', obtained by The Sun-Herald, to the office of the former state environment minister.

Last week the department sought a court injunction that could see Sydney's worst serial dumper, Dib Hanna, of Colyton, jailed if he was caught one more time. Mr Hanna was fined $133,000 last year for four dumping cases involving asbestos.

Mr Lamberton said: ''All you need to get going with illegal dumping is to own a truck.'' The department said it was strengthening operations for a crackdown on rogue operators.

Industry sources said some site owners were being duped into accepting contaminated soil; others were being threatened or offered cash to accept the waste. Recently uncovered cases included the toxic remnants of illicit drug laboratories.

Industry operators say fines are small and the consequences not harsh enough.

''It's like getting a speeding ticket,'' said a waste operator who did not want to be named. ''In a simple risk-and-reward trade-off. Unscrupulous operators accept they will pay fines and court costs in order to enjoy significant cost advantages.''

Asbestos Diseases Foundation president Barry Robson has long urged council tip sites to take asbestos waste free, particularly from households. He said the public health risks of illegally dumped material outweighed the cost to local government of its proper disposal.

Raymond Saadeh, president of St George United Soccer Club, which leases the oval where asbestos-contaminated soil was found, said he had ordered clean sand to prepare the field for top-dressing. He said he did not know who was responsible for the dumping.

In the past year in Rockdale, seven people have been fined $750 each for dumping offences and one company has been fined $5000. Six other cases are being investigated.

A Rockdale City Council spokesman said an estimated 582 tonnes of illegal waste, including 7.71 tonnes of asbestos, would be dumped by June, with the clean-up bill about $220,000. However, department waste management manager Chris McElwain said it had just had its best year in enforcement, conducting 730 inspections and issuing 42 clean-up notices, of which only 12 were outstanding.

Mr McElwain said NSW had the toughest fines in the country and the department would expand enforcement campaigns this year to the north and south coasts, up to the Queensland border. He said it was vigorously pursuing cases in the shame file, including the alleged dumping of 200 tonnes of asbestos-contaminated soil at a property in Wollondilly Shire.

Wollondilly Council has taken civil action against landowner Foxman Environmental Development Services and its director, Phillip Foxman, who also runs the waste company Botany Bay Recyclers. Mr McElwain said the dumping was also the subject of a criminal investigation.

But Mr Foxman told The Sun-Herald the department had conducted a ''witch-hunt'' against him.

''There are a number of vicious, nasty and unethical people in the organisation,'' he said. ''I don't consider this illegal dumping. I have a development approval for the site to build a house and a pool … and I am a licensed recycling contractor.''

The Sun-Herald does not suggest Mr Hanna, Mr Foxman, or his companies, have any involvement with organised criminals linked to bikie groups or otherwise.

Do you know more about who is involved in illegal dumping?

Email: n.obrien@fairfaxmedia.com.au