DURING a survey of the wildlife in Cinderford's Northern Quarter, a sink hole 15 metres wide has been found – just yards from Steam Mills Primary School.

The hole, which was found during a wildlife survey of the Northern Quarter site, was examined by former Home Office mines surveyor Paul Morgan - who stated that he had 'real safety concerns' over the state of the stability of the ground in the area.

Mr Morgan, who is a member of community organisation Dean Forest Voice, said: "This appears to be a substantial mine entry which is approximately fifteen metres wide, funnelling down some four metres to the top of a shaft possibly three metres in diameter - the depth was too dangerous to ascertain.

"There was evidence of youngsters picnicking in the area and this gives real safety concerns. Ground movement is not a rare occurrence in this intensively mined area. Following the Duck Pit collapse by the cricket club, and the recent Brierley slippage, this makes it the third time in two years."

Sink holes are the result of sub-surface ground movement, often linked to the collapse of old mine workings.

Dean Natural Alliance claim that over a dozen old sink holes have been found during wildlife surveys in the recent past, and they have reiterated their stance that the existence of the holes means that: "This is a key reason for Cinderford's Northern Quarter being wholly unsuitable for any development."

In a statement, the Home and Communities Agency (HCA), the Government department which is overseeing the Northern Quarter development, said: "The HCA is due to undertake further detailed ground investigation work across the site, which will provide the in-depth technical information needed to inform the construction methods use for the proposed development. This follows an earlier phase of investigation which was completed last year and did not find any issues in relation to mine workings that would present an engineering risk to the first phase of construction work.

"This will be kept under review and is an absolutely crucial park of the Northern Quarter development, which stands to unlock £100m in investment, new jobs and a state-of-the-art sustainable college development, which people in the Forest of Dean have told us they want to see."

Andrew Bluett of Gloucestershire Naturalists' Society said in a statement: "There is no doubt that historically the site has been extensively mined both with shafts and opencast extraction, and has been the site of opencast clay extraction for the local brickworks.

"It is believed that there is a significant aquifer under the area that could aggravate the deterioration of the ground in some areas."

He added: "Estimates vary, but the belief is that there are over 130 uncapped shafts on the site - and could be more than twice that number."