Investigators say they've tracked down some of the 17,000 tonnes of asbestos-contaminated waste removed from a Sydney construction site and illegally dumped.

But the location of much of the contaminated material is still unknown.

NSW Police believe some of the waste is on a rural property in Kulnura about 70 kilometres north of Sydney’s CBD.

“Investigators believe the illegal dumping operation is linked to organised crime,” a police spokesperson said in a statement on Wednesday.

Detectives in mid-August arrested a 48-year-old waste disposal company director at Sydney Airport as he tried to flee the country.

They allege his company removed 600 truckloads of asbestos-contaminated building waste from the Green Square redevelopment from mid-2016 and dumped it illegally.

Police and investigators from the NSW Environment Protection Authority on Wednesday searched the Kulnura property on the Central Coast.

The property’s owners told police they believed the material was clean fill.

Aerial footage, aired by the Seven Network on Wednesday afternoon, showed investigators in masks and gloves surveying the rural land while excavators shifted mounds of dirt.

Kulnura property owner Soraya Van Tilborg says she doesn’t even want to think about what her family may have been exposed to.

“We spent ages working to get this property. It all looked very legitimate, everything seemed in order,” she told the Seven Network on Wednesday.

“I don’t want to even think about it.”

Soil samples are expected to confirm the presence of asbestos and “large-scale remediation will be required”, a police spokesperson said.

A NSW Police spokeswoman said it’s unclear how much of the missing 17,000 tonnes of waste could be at the Kulnura site.

SafeWork NSW licensed asbestos assessor Tony Milligan said contaminated waste can only legally be disposed of at EPA-licensed landfill facilities.

“(But) the high cost of removal of asbestos-containing materials and charges to legally dispose of it places a huge responsibility on those operating in the industry and the ‘rewards’ for misusing that responsibility are irresistible to some,” the managing director of Practical Environmental Solutions said.

The 48-year-old charged over the illegal Green Square dumping is facing fraud offences worth almost $4 million.

The EPA on Wednesday separately announced it had commenced seven prosecutions in the Land and Environment Court in relation to the alleged illegal disposal of waste – including asbestos – at Arcadia in NSW.

By Perry Duffin