Road users are advised that the M11 remains closed southbound between Junctions 7 and 8 following a significant chemical spill yesterday evening.

It was hoped that the road would be reopened by 9am but travellers are advised to check the route and plan their journeys in advance.

A 25 metre section of the southbound carriageway and the gulleys of the northbound carriageway were covered with a chemical foam after a lorry overturned at around 5pm on Thursday evening.

The foam started to solidify on contact with the carriageway and also penetrated the surface.

Operations manager Ian Jobson said: “We have been working throughout the night to ensure the foam is removed as quickly and safely as possible but this is a complicated operation.

“The nature of the chemical involved has meant that we have had to ensure none of it reaches the water course and so the clean up operation involves jetwashing the carriageway surface and then using gulley suckers to ensure all liquid is removed and can be safely and environmentally disposed of away from the scene.

“We are working as quickly as we can and we would like to thank road users for their patience while we carry out this important work.”

At the request of Essex County Fire & Rescue Service, a 150 metre exclusion zone was put in place until it could be established that the foam was not releasing toxic fumes.

Divisional officer Terry Povey said: “The chemicals are low risk to the health of people but they can have a negative environmental impact so we are containing the leak. We have blocked the drains and are standing by awaiting the arrival of a clean up team from the highways agency to come and clear the roadway.

“This has been downgraded from a chemical incident because the chemicals do not pose a significant health risk. It is now a matter of getting the road cleared so it can re-open.”

The Environment Agency were also at the scene until 1am this morning carrying out assessments on environmental impact and drains alongside the carriageway were covered to ensure the chemical did not reach the water courses.

The northbound carriageway opened at 5.50am this morning.

Southbound traffic is advised to follow the hollow square symbol on diversion signs which will direct traffic to leave the M11 at Junction 8 and travel along the A120 to Puckeridge, then join the A10 and continue to Harlow to join the A414 and rejoin the M11 at Junction 7.