A combination of Doosan, Bobcat and Montabert products is helping Forest Pennant Limited to keep up with demand for Natural Pennant stone from the company’s quarry in the Royal Forest of Dean in Gloucestershire in the UK.
The machines include Doosan DX520LC and DX340LC crawler excavators, a Doosan DL420 wheel loader, a Bobcat E80 excavator and a Montabert XL2600 Blue Line hydraulic breaker.
Natural Pennant stone from the Royal Forest of Dean has been used as a traditional building and paving material for centuries. Many of the oldest cities and towns in the South of England and South Wales have been paved with Pennant stone, which has a naturally hard-wearing surface with a good slip skid resistance, though it can also be specified with a shot blasted finish which gives an enhanced slip skid resistance.
The first stage in the process to win the stone utilises the Doosan DX520LC excavator to remove overburden down to the layers of Pennant stone to a depth of 18-19 m from the top of the quarry. The Montabert XL2600 hydraulic breaker mounted on the DX340LC excavator is then used to remove the layers of rock that lie above the layers of Pennant stone to form a work bench to work on to quarry the stone.
The overburden and rock produced by the two Doosan excavators is loaded into an articulated dump truck which carries it away from the face to a dumping point higher up in the quarry. Here the material is separated using a screening bucket and provides a source of building stone and cropped walling stone, which also form part of the product range available from Forest Pennant.
When it has been formed, the work bench provides a platform on which the Bobcat E80 excavator can work. Blocks of blue and mixed colour Pennant stone are produced in the quarry using the traditional plug and feather method, which reduces the risk of fracture. The E80 is equipped with a drilling head and compressor system to produce holes in the Pennant stone, which are then utilised to split the rock using a hydraulic feathering machine.
Next the DX340LC excavator is used to lever 12-14 tonne blocks of Pennant stone away from the quarry face from where they are carried by the Doosan DL420 wheel loader to the top of the quarry to be loaded on to lorries to be taken to the Forest Pennant factory a mile away in the forest for further processing.
Natural Pennant stone from the Royal Forest of Dean has been used on a variety of historically important projects such as Hampton Court and the interiors of the St Johns and Exeter Colleges at Oxford University. More recently, Pennant Paving has been laid at Cheltenham Ladies College, The British Empire Museum in Bristol, Cardiff Memorial Park, Bristol and Gloucester Docks, Maesteg Town Centre, Minehead High Street, St John’s Church yard in Cardiff and Tewkesbury Town Centre.