A CHEMICAL company responsible for an illegal gas release that left nearby homes coated in white powder has been fined £10,000.

The incident, which took place on December 1, 2010 at Ineos, in Newton Aycliffe, County Durham, sent 56 tonnes of gas, particles and steam into the air, with some settling on homes and gardens in the nearby Chestnuts housing estate.

Residents said they heard a sound like a jet engine coming from the plant, followed by a massive cloud of steam.

Darlington Magistrates’ Court heard yesterday that the accident took place shortly after 4.20pm during the production of polyvinylchloride (PVC) in section D of the plant.

Craig Burman, prosecuting on behalf of the Environment Agency, told the court the chemical reaction to create the product went out of control when a pump failed.

An alarm sounded, which was ignored by a worker.

When staff tried to manually stop the reaction by flooding it with chemicals, they were unable to because winter temperatures had frozen the pipes.

To prevent a “catastrophic failure”, the last option was to release the chemicals into the atmosphere using an emergency relief valve.

The cloud of chemicals, which contained particles of PVC and a gas called vinyl chloride monomer (VCM), drifted west towards the Chestnuts.

Once snow on the ground had melted, residents discovered a fine white powder coating their homes and gardens.

The court heard that while VCM has the potential to be carcinogenic, the amount of chemicals released posed no health or environmental threat.

Rob Elvin, in mitigation, said Ineos cleaned up the powder and has made changes at the plant to prevent another accident.

The company pleaded guilty to the illegal release and is inviting residents of the Chestnuts to tour the plant to study the improved safety procedures.

A spokesman said last night: “The release occurred from use of an emergency relief system designed to protect a PVC manufacturing process from excessive pressure.

“The company has accepted that on this occasion it breached a particular condition of its operating permit, and has reiterated its apology to local residents for any concern the incident may have caused.”

Councillor Gerald Lee, who helped set up the Chestnuts Resilience Group, which liaises with local businesses such as Ineos, said: “We are very conscious of the fact that Ineos brings a lot to the North-East economy.

“But we are also conscious that it needs to be a good neighbour and it is important that it works with residents because it is them who are affected by incidents like this.”

As well as a £10,000 fine, Ineos was ordered to pay £6,000 costs.