It wasnt until a raid by Penrith City Counci in November 2015, that the yard gates were opened to reveal the health and environmental threat on Sydneys suburban fringe.

Toxic firefighting foam, shipping containers full of used oil filters, 300,000 litres of oil sludge, 40,000 litres of grease, 16 tonnes of contaminated soil and 90,000 litres of oil contaminated water.

More than 400 contaminated plastic bins, 200 contaminated steel drums, 12,000 litres of corrosive liquid and an unlined dirt pit dug into the back corner of the yard where waste oil was dumped.

The Charles St property was owned by Truegain, also known as Australian Waste Oil Refineries (AWOR), a serial environmental offender. The legacy of 13 years of Truegain ownership was a site laid waste by pollution.

Truegains atrocious environmental record, exposed by a Newcastle Herald investigation, included oil and liquid waste dumping into surrounding waterways and properties dating back decades.

A former Sydney-based Truegain employee described the St Marys site as shocking. The mud was oil at St Marys, he said. It was that badly contaminated.

Workers said Truegain trucks plied back and forth between St Marys and Rutherford for more than a decade hiding waste the company did not want authorities to find during planned inspections.

It was their dirty little secret, a former truck driver said. They hid a lot of stuff at St Marys that they didnt want anyone to know about. It went both ways between Rutherford and Sydney depending on who was looking at which place at the time.

Another worker said he was so disgusted with the pollution at the St Marys yard he called the EPA to report it, but he never heard anything back.

According to an EPA report obtained by the Herald, waste oil and sludge was being stored in open containers across the premises, collecting rainwater and overflowing.

Containers used to store waste oil and oil products are broken with the products leaking onto the ground, the report states. An unlined waste oil detention pit has been dug into the earth to collect contaminated stormwater causing land pollution and potentially water pollution.

A Penrith City Council spokesman described the property as high risk. He said Truegain was ordered to immediately cease operations and a clean-up notice issued.

It was then that workers said truckloads of waste started being shipped up the M1 to Rutherford for storage or to be fed through the plant to get rid of it.

All this stuff was coming from St Marys because they were in trouble and needed to get rid of it, a former employee said. Then a few months later they get caught releasing firefighting foam into the sewer and the whole operation goes down the drain. You have to question the timing of it all.

Several employees said they heard so much wastewater was being dumped from the St Marys yard that stormwater drains down the street started spewing foam.

In February 2016, Truegain was caught by Hunter Water discharging per- and polyfluoroalkyl chemicals (PFAS), at the heart of the Williamtown red zone environmental scandal, into the Maitland sewer system from its Rutherford plant.

The firefighting foam chemicals were detected after a Hunter Water compliance officer questioned why foam was building up on a storage tank and a worker said he believed it was caused by contaminated groundwater Truegain had been collecting that contained fire retardant.

The site was disconnected from the sewer and Truegain lost its gas supply soon after because it did not pay the bill.

Two months later the EPA suspended its environmental protection licence, because Trugains pollution control equipment was gas powered. The company went into liquidation in September 2016.

Workers said in the weeks before the company was caught releasing PFAS into the sewer, truckloads of waste, including huge volumes of wastewater from 1000-litre bulk containers, was arriving at Rutherford from St Marys due to the massive clean up sparked by the council raid.

One former worker said the plant was foaming like a bubble bath at the time.

After Truegain folded, liquidator Jamieson Louttit and Associates found 2000 litres of Aqueous Film Forming Foam (AFFF) still at the St Marys yard.

AFFF is a fire retardant manufactured by 3M and used by the military, commercial airports, fire brigades and heavy industry for decades, and contains PFAS chemicals.

The man-made chemicals have been described as virtually indestructible in the environment.

In May, the EPA revealed PFAS had been found in Stony, Fishery and Wallis creeks which run to the Hunter River. The level of PFAS found in Stony Creek, which runs along the back of Truegains Rutherford site, was 22 times the recommended drinking water guideline.

An EPA spokesman said that a containment system housing PFAS at the Truegain oil refinery at Rutherford overflowed during heavy rain in March prompting testing that detected PFAS in the waterways.

Residents along Stony Creek have been told to avoid consuming eggs, milk and home-slaughtered livestock where chickens or stock have been watered with, or have access to, creek water.

Those along Fishery Creek downstream of Stony Creek and Wallis Creek downstream of Fishery Creek are urged to avoid eating home-slaughtered livestock.

An EPA spokesman said it was overseeing the Rutherford plant to ensure no further leaks.

There are still huge quantities of PFAS contaminated wastewater in tanks at the site and other toxic waste.

The St Marys site was sold by Truegain liquidator Jamieson Louttit and Associates for $2.6 million in February 2017.

It has since been remediated by the new owners who specialise in cleaning contaminated sites around Australia.