It could take up to nine years to clear the Bersham site

Councillors voted not to remove the tip at the former Bersham Colliery in Rhostyllen which closed 21 years ago.

The decision followed a plea by Cadw to keep the tip because of its importance to the "appreciation of the development of north east Wales."

Wrexham's planners recommended removing the 6m tonnes of shale, which could be sold on to the building industry.

Bersham Colliery was one of the most important in the coalfield in the 19th and 20th centuries Cadw

In a report considered by councillors on Monday, chief planning officer Lawrence Isted added: "I am satisfied that the other material considerations outweigh the retention of the tip."

The report said it could take between seven and nine years to clear the spoil.

The unburnt black shale and burnt red shale could be extracted and sold on to the construction industry.

However, councillors voted against the plans after Cadw, the agency responsible for preserving the culture and heritage of Wales, said it wanted the tip to remain.

In a letter to Wrexham Council it said: "Bersham Colliery tip is a remnant of the Denbighshire coal mining industry which formed an important part of the industrial history of north east Wales."

"Understanding"

It added: "The tip is one of the few remaining coal tips from the coalfield, and almost certainly the most important from the perspective of its contribution to a surviving industrial complex.

"Bersham Colliery was one of the most important in the coalfield in the 19th and 20th Centuries and the survival of this one reasonably intact complex is therefore valuable for our contemporary understanding and appreciation of the development of north east Wales."

The mine closed in 1986, putting 300 miners out of work.

At one time there were 90 deep mines in Wrexham and 200 in neighbouring Flintshire.

The company behind the plan to dismantle the tip and process the waste, Midlands-based Bersham (Glenside) Ltd, wanted to use the burnt shale to process into a lightweight aggregate.

It said the unburnt material could be used in the cement-making process.

Before the meeting, Mike Killet, the company's technical director, said the company wanted to promote the lannd as a mixed-use development site once the area had been cleared.