MORE than 50 years of explosive extraction methods were brought to an end yesterday with the last ever blast at a Portland quarry.

Albion Stone Quarries has been working the Bowers Quarry site since it took over from Kingston Minerals in 1979 and its Bower Whitbed and Basebed stone is distributed throughout the world.

Blasting techniques have been used in the open mine for decades, but discussions with local residents' groups made it clear that changes in the extraction process were necessary to reduce noise, dust and vibration levels. So the company invested heavily in more modern mining equipment.

The new methods, which use jet belts and wire saws, are set to benefit the environment, the local community and the company itself with less noise and dust pollution and better yields.

Managing director Michael Poultney said: "We feel it is our duty as a responsible quarrying company to implement changes that would produce significant environmental improvements to the island.

"The cessation of blasting in all Albion's quarries and the acquisition of the jet belts and wire saws form part of our continuous investment to ensure the adoption of modern stone extraction methods that respect the environment and the community."

Jet belts operate like a giant chainsaw by cutting through the rock whilst moving on a conveyor, and wire saws work on the same principal as a cheese wire by slicing the stone - both techniques produce cleaner and more superior blocks of stone.

Mr Poultney said: "Architects and masons who come to have a look at our products can now see the quality of the stone."

Modernisation in quarry extraction processes has taken place in major quarrying areas such as Carrara in Italy and some parts of Spain where they have been using this type of equipment for 10 years with annual production levels of up to two million cubic metres.

On Portland, new processes have gradually been phased in over a five-year period, costing almost half-a-million pounds to convert.

When blasting was the main method of extraction, around three explosions a day were needed, which often sparked complaints from local residents.

Production director Pat George said: "Even the most carefully designed blast will create a certain amount of nuisance to local residents. The environmental benefits will be extremely significant."

Concerns have been raised about new mining techniques but Albion has reassured residents that new methods would not cause any problems with land stability.

Head of planning for Dorset County Council Andrew Price had the honour of detonating the final blast to break up a pile of large blocks so they could be removed from the site.